“AdBlue fault – top up additive. 1200 km until engine won’t restart.” If you drive a Peugeot Boxer (2015+ Euro 6), you’ve probably seen this message at least once. Peugeot Boxer AdBlue problems are notoriously common—from the infamous P20EE fault code that appears even with a full tank, to AdBlue pumps that fail at 60,000 miles, to temperature sensors that read -40°C in the middle of summer. The frustrating part? The Boxer shares its platform, engine and AdBlue system with the Citroën Relay and Fiat Ducato, so all three vans suffer from identical faults. This guide covers the 9 most common Peugeot Boxer AdBlue problems (2015–2025 models), what causes them, how to diagnose which component has failed, quick fixes you can try yourself, and when you need specialist help. We’ll also cover the differences between Euro 6b (2015–2019) and Euro 6d (2019+) models, because the later vans have additional sensors and more complex fault patterns.
9 most common Peugeot Boxer AdBlue problems (2015–2025)
1. P20EE fault code – “SCR NOx catalyst efficiency below threshold”
Symptoms:
- “AdBlue fault – top up additive” message on dash
- Countdown: 1200 km → 800 km → 50 km → engine won’t restart
- Fault appears even with a full AdBlue tank
- Most common fault on 2015–2019 Boxers (Euro 6b)
What causes it:
- Faulty AdBlue quality sensor (60% of cases) – reads “empty” or “poor quality” even when tank is full of fresh AdBlue
- Contaminated AdBlue (20% of cases) – water, diesel or wrong concentration triggers SCR efficiency fault
- Failed NOx sensor (10% of cases) – can’t accurately measure NOx reduction, so ECU thinks SCR isn’t working
- Blocked AdBlue injector (10% of cases) – crystallised AdBlue prevents proper dosing
Quick fix (try this first):
- Top up the AdBlue tank to completely full (20 litres)
- Drive for 20–30 minutes on a motorway at 60+ mph (high exhaust temperature can clear temporary faults)
- Turn the engine off, wait 2 minutes, restart
- If the countdown has stopped reducing or the warning has cleared, the fault was temporary
If that doesn’t work: The quality sensor needs cleaning or replacement. Access is via the AdBlue tank filler cap (remove the blue cap, sensor is inside the neck on a long probe). Cost: £80–£200 for sensor cleaning/replacement + £50–£80 code clearing.
2. AdBlue pump failure (common at 60,000–100,000 miles)
Symptoms:
- “AdBlue system fault” message
- Fault code P20E8 (reductant pressure too low)
- AdBlue consumption drops to zero (tank level doesn’t go down)
- You can’t hear the AdBlue pump priming when you turn the ignition on (should hear a faint whirring for 10–15 seconds)
What causes it:
- Pump motor failure (brushes worn out—common at 60,000–100,000 miles on Boxers)
- Blocked pump filter (crystallised AdBlue or contamination)
- Corroded pump connector (green/white deposits on pins)
- Running the AdBlue tank completely dry (air damages pump seals)
How to test the pump:
- Turn the ignition on (engine off)
- Listen for the pump—it’s under the van, driver’s side, mounted on the AdBlue tank
- You should hear a high-pitched whirring for 10–15 seconds
- If you hear nothing, check the pump fuse (fuse box under the dash—check owner’s manual, usually F37 or F38)
- If the fuse is intact and you still hear nothing, the pump has failed
Replacement cost: £300–£550 for the pump (Bosch/Pierburg genuine: £350–£500, aftermarket: £250–£400) + £100–£180 fitting (2–3 hours labour).
3. AdBlue temperature sensor fault (P20E9)
Symptoms:
- “AdBlue system fault” message
- Fault code P20E9 (reductant temperature sensor circuit)
- Diagnostic scanner shows AdBlue temperature as -40°C or -48°C even in summer
- Warning often appears in cold weather, then clears when it warms up
What causes it:
- Failed temperature sensor in the AdBlue tank or pump
- Corroded sensor wiring or connector
- Water ingress into the sensor connector (common on vans parked outdoors)
Quick fix (if fault is intermittent):
- Jack up the van (driver’s side) and locate the AdBlue pump/tank under the van
- Inspect the temperature sensor connector (usually integrated into the pump or tank sensor)
- Spray with electrical contact cleaner and dry thoroughly
- Check for green/white corrosion on pins—clean with a small wire brush
- Clear codes and test
If that doesn’t work: Temperature sensor needs replacing. On most Boxers, the sensor is integrated into the pump or tank sensor assembly, so you may need to replace the whole pump (£300–£550) or tank sensor (£80–£200).
4. AdBlue heater fault (winter only – P13DF)
Symptoms:
- “AdBlue system fault” appears only when temperature drops below 0°C
- Fault code P13DF (reductant heater control circuit)
- Warning clears when the van warms up or weather improves
- Common on 2015–2017 Boxers (early Euro 6b models)
What causes it:
- Failed heater element in the AdBlue tank or pump (AdBlue freezes at -11°C, heater prevents this)
- Blown heater fuse or corroded heater wiring
- Heater relay failure (located in fuse box under bonnet)
Quick fix (temporary):
- Park the van indoors or in a heated garage overnight
- Start the engine and let it idle for 15–20 minutes to warm the AdBlue system
- If the warning clears, the AdBlue was frozen but the heater is working—no repair needed
- If the warning stays on even after warming up, the heater has failed
Replacement cost: Heater element is usually integrated into the pump assembly, so you need to replace the whole pump (£300–£550 + fitting). On some models the heater is separate (£120–£250 + fitting).
5. AdBlue injector blockage (P20BD)
Symptoms:
- “AdBlue system fault” message
- Fault code P20BD (reductant injector circuit) or P20EE (SCR efficiency)
- AdBlue consumption drops to zero or very low
- White smoke from exhaust (unburned AdBlue vapour)
- Common on vans used for short trips (city deliveries, courier work)
What causes it:
- Crystallised AdBlue blocking the injector nozzle (happens when the injector doesn’t reach full operating temperature—short trips)
- Contaminated AdBlue (sediment blocks the nozzle)
- Failed injector solenoid (won’t open to spray AdBlue)
Quick fix (try this first):
- Drive the van on a motorway for 30–40 minutes at 60+ mph
- High exhaust temperature (400–600°C) can burn off light crystallisation
- If the warning clears after a long drive, the injector has self-cleaned
If that doesn’t work: Injector needs professional cleaning (ultrasonic bath + compressed air: £100–£180) or replacement (£250–£450 for injector + £80–£150 fitting).
6. AdBlue tank contamination (P204F)
Symptoms:
- “AdBlue quality poor – top up additive” message
- Fault code P204F (reductant system performance) or P20EE
- Warning appeared immediately after topping up (not before)
- AdBlue in the tank looks cloudy, yellow-tinged or has sediment
What causes it:
- Contaminated AdBlue (water, diesel, screenwash or wrong concentration)
- Old or expired AdBlue (over 18 months old, or stored in direct sunlight)
- Using opened or partially-used bottles (exposure to air degrades urea concentration)
- Accidentally adding diesel or screenwash to the AdBlue tank
Fix:
- Drain the AdBlue tank completely (siphon pump or drop the tank—access under the van, driver’s side)
- Flush with 5 litres of fresh AdBlue, then drain again
- Refill with fresh, sealed ISO 22241 AdBlue (15–20 litres)
- Clear fault codes with a diagnostic scanner (Peugeot/Citroën Diagbox or generic OBD2)
- Drive for 20–30 miles to allow the SCR system to recalibrate
Cost: £30–£50 for fresh AdBlue + 1–2 hours labour if you do it yourself. Mobile service or garage: £150–£300 for drain, flush and refill.
7. NOx sensor failure (P2201, P2BAD – high mileage)
Symptoms:
- “AdBlue system fault” message
- Fault codes P2201 (NOx sensor circuit range/performance) or P2BAD (NOx sensor circuit low)
- Van has 100,000+ miles
- AdBlue consumption is normal (tank level drops as expected)
- No other obvious faults (pump, injector, quality sensor all test OK)
What causes it:
- NOx sensor degraded (soot, oil or carbon contamination)
- Sensor calibration drifted out of spec (end of lifespan—100,000–150,000 miles)
- Poisoned sensor electrodes (from contaminated AdBlue or poor-quality diesel)
Which sensor has failed: Boxers have two NOx sensors—upstream (before SCR) and downstream (after SCR). Check fault codes:
- P2201 / P2BAD (Bank 1 Sensor 1): Upstream sensor
- P2203 / P2BAF (Bank 1 Sensor 2): Downstream sensor
Can you clean it? Sometimes—see our NOx sensor cleaning guide. Success rate: 30–40% for external contamination, 0% for internal sensor failure.
Replacement cost: £300–£600 per sensor (Bosch/Continental genuine: £400–£600, aftermarket: £250–£450) + £60–£120 fitting + £50–£100 coding (Diagbox required to calibrate new sensor).
8. Wiring and connector faults (P207F, intermittent warnings)
Symptoms:
- Intermittent AdBlue warnings (comes and goes, especially over bumps or in wet weather)
- Warning clears after restarting the engine, then returns after 10–100 km
- Multiple fault codes that don’t match the symptoms
- Fault code P207F (reductant level sensor circuit)
What causes it:
- Corroded connectors (green/white deposits on pins—common on vans parked outdoors or driven in winter with road salt)
- Chafed wiring (rubs against chassis or exhaust—common near the AdBlue tank under the van)
- Loose connector (vibration causes intermittent contact)
- Water ingress into connector (poor sealing or cracked connector housing)
Quick fix:
- Jack up the van (driver’s side) and inspect all AdBlue system connectors (tank sensor, pump, temperature sensor, injector)
- Look for green/white corrosion on pins, or white crystals (dried AdBlue)
- Disconnect each connector, spray with electrical contact cleaner, scrub with a small brush, dry thoroughly
- Check wiring for chafing, breaks or exposed copper—repair with solder and heat-shrink tubing
- Apply dielectric grease to connector pins to prevent future corrosion
- Clear codes and test
Professional repair cost: £80–£180 for connector cleaning and wiring repair (1–2 hours labour).
9. DPF regeneration triggering false AdBlue faults
Symptoms:
- “AdBlue system fault” appears during or immediately after a DPF regeneration
- Warning clears after 20–50 km of driving
- Fault code P20EE (SCR efficiency) but no actual AdBlue system fault
- Common on 2019+ Euro 6d models with close-coupled DPF/SCR
What causes it:
- During DPF regeneration, exhaust temperature spikes to 600–700°C
- This temporarily affects NOx sensor readings (sensors are calibrated for 200–500°C normal exhaust temps)
- ECU sees abnormal NOx readings and triggers a false P20EE fault
- Fault is temporary and self-clears once exhaust temperature normalises
Fix:
- If the warning appears during or after a regen, drive normally for 20–30 km
- The warning should clear automatically once the exhaust cools
- If it doesn’t clear, use a diagnostic scanner to check if the fault is still “active” or just “stored”
- Clear stored codes and test
Prevention: Ensure DPF regenerations complete properly (don’t interrupt regens by turning off the engine). If your van does lots of short trips, schedule a monthly motorway run (30–40 minutes at 60+ mph) to allow a full regen cycle.
Peugeot Boxer AdBlue problems by model year
2015–2019 Boxer (Euro 6b – 2.0 BlueHDi)
Common problems:
- P20EE fault (most common): Quality sensor failures, contaminated AdBlue
- Pump failures: High failure rate at 60,000–100,000 miles (earlier than later models)
- Heater faults: P13DF common in winter on 2015–2017 models
- Injector blockage: Common on city/short-trip vans
Known issues:
- Early Euro 6b Boxers (2015–2017) have a high AdBlue pump failure rate—Peugeot issued a service bulletin recommending pump inspection at 80,000 km
- Quality sensor (part number 1606488480) is prone to crystallisation—aftermarket sensors (Bosch, VDO) are more reliable
- AdBlue tank capacity: 17 litres (smaller than Ducato/Relay—requires more frequent top-ups)
2019–2022 Boxer (Euro 6d-TEMP – 2.2 BlueHDi)
Common problems:
- NOx sensor faults: More common than Euro 6b models (two sensors instead of one on early models)
- DPF-related false faults: P20EE triggered during regenerations
- Temperature sensor faults: P20E9 more common due to additional temperature monitoring
Known issues:
- Euro 6d models have a more complex AdBlue system (additional sensors, closer integration with DPF)
- Software updates available for false P20EE faults during DPF regens—check with Peugeot dealer
- Improved pump design (fewer failures than Euro 6b), but still expect replacement at 100,000–150,000 miles
2022–2025 Boxer (Euro 6d-FINAL – 2.2 BlueHDi)
Common problems:
- Software glitches: Intermittent warnings that clear after restart (ECU software bugs)
- NOx sensor faults: Still common at high mileage (100,000+ miles)
- Quality sensor faults: Less common than earlier models (improved sensor design)
Known issues:
- Latest models have improved reliability, but still share the same basic AdBlue system as earlier Boxers
- AdBlue tank capacity increased to 20 litres (2023+ models)
- Software updates available for intermittent faults—always check for latest ECU software version
How to diagnose Peugeot Boxer AdBlue faults (step-by-step)
Step 1: Read the fault codes
You need a diagnostic scanner that can read Peugeot/Citroën-specific codes. Options:
- Basic OBD2 scanner: £20–£50 (Halfords, Amazon). Will read generic codes (P20EE, P204F) but not manufacturer-specific codes or live data.
- Peugeot/Citroën Diagbox: Professional diagnostic software (requires dealer tools—£2,000+). Can read all codes, live data, perform resets and coding.
- Generic professional scanner: Launch, Autel, Snap-on (£300–£1,500). Can read most Peugeot codes and live data.
- Mobile diagnostic service: We carry Diagbox and Autotuner—can read all codes, live data and perform resets on-site. Cost: £50–£80 for diagnostics.
Key codes to look for:
- P20EE / P204F: Quality sensor, contamination, or SCR efficiency
- P20E8: Pump failure or air in system
- P13DF / P20E9: Heater or temperature sensor fault
- P20BD: Injector fault
- P207F: Wiring or quality sensor circuit fault
- P2201 / P2BAD: NOx sensor fault (upstream or downstream)
Step 2: Check AdBlue level and quality
Even if the dash says “AdBlue empty,” physically check the tank:
- Remove the blue AdBlue filler cap (usually next to the diesel filler, or under the bonnet on some models)
- Use a torch to look inside the filler neck—you should see clear, colourless fluid
- Top up with at least 10 litres of fresh, sealed ISO 22241 AdBlue
- Check the AdBlue looks clear (not cloudy, yellow or with sediment)
- Restart the engine and check if the warning clears or countdown stops reducing
Step 3: Check live data (if you have Diagbox or professional scanner)
With the engine running, check:
- AdBlue level sensor: Should read 30–100% (matches actual tank level)
- AdBlue temperature: Should climb from ambient (20°C) to 60–80°C after 10 minutes of driving
- AdBlue pressure: Should read 4–6 bar when the engine is running
- NOx sensor readings: Upstream 200–800 ppm, downstream 0–100 ppm
- AdBlue dosing rate: Should be 0.5–2% of fuel consumption (varies with load and speed)
If any reading is stuck at 0, maximum, or doesn’t change, that component has failed.
Step 4: Inspect components under the van
Jack up the van (driver’s side) and inspect:
- AdBlue tank: Behind the rear wheel, driver’s side. Check for leaks, cracks, or corrosion.
- AdBlue pump: Mounted on the tank. Check connector, listen for pump priming when ignition is turned on.
- Wiring: Follow the wiring from the tank/pump forward to the engine bay. Check for chafing, breaks, corrosion, or white crystals (dried AdBlue).
- AdBlue injector: Located in the exhaust downpipe (after turbo, before DPF/SCR). Check connector and wiring.
Quick fixes you can try before calling a specialist
Fix 1: Top up and drive (for P20EE with low AdBlue)
For: P20EE or P204F faults when AdBlue level is low (under 25%).
- Top up the AdBlue tank to completely full (17–20 litres)
- Drive on a motorway for 20–30 minutes at 60+ mph
- High exhaust temperature helps the SCR system recalibrate
- Turn off the engine, wait 2 minutes, restart
- Check if the countdown has stopped or warning has cleared
Success rate: 40–50% for temporary sensor glitches or low-level faults.
Fix 2: Clear codes and reset (for one-off faults)
For: Warnings that appeared after a one-off event (contamination, running dry, battery disconnect).
- Use a diagnostic scanner to clear all fault codes
- If you have Diagbox, perform an AdBlue system reset (forces ECU to re-learn all sensor values)
- Drive for 20–30 minutes to allow the system to recalibrate
- Re-check for fault codes after 50 km
Success rate: 30–40% if the root cause was temporary.
Fix 3: Clean the quality sensor
For: P20EE, P204F or P207F codes with “AdBlue empty” message when tank is full.
- Remove the blue AdBlue filler cap
- The quality sensor is inside the filler neck on a long probe (you may need to remove a retaining clip or twist to release it)
- Pull the sensor out carefully (it’s connected by a wire—don’t pull too hard)
- Rinse the sensor probe in warm water, scrub gently with a soft brush
- Dry thoroughly with compressed air or kitchen roll
- Clean the connector with contact cleaner spray
- Refit, clear codes, test
Success rate: 50–60% for sensors that are just dirty (not failed internally).
Fix 4: Check and clean connectors
For: Intermittent faults (P207F, P20E9, warnings that come and go).
- Jack up the van (driver’s side) and locate all AdBlue system connectors
- Disconnect each connector, inspect for corrosion (green/white deposits) or white crystals
- Spray with electrical contact cleaner, scrub with a small brush, dry thoroughly
- Apply dielectric grease to pins to prevent future corrosion
- Reconnect, clear codes, test
Success rate: 60–70% for wiring/connector faults.
When to call a mobile specialist
Call for professional help if:
- You’ve tried the quick fixes above and the warning won’t clear
- The countdown is under 100 km (urgent—engine won’t restart once it hits zero)
- You don’t have diagnostic tools to read codes or check live data
- The fault is intermittent and hard to diagnose without live data monitoring
- Multiple fault codes are stored (suggests complex fault or multiple failed components)
- You need parts replaced (pump, sensor, injector) and don’t have tools or access to lift the van
- You need Diagbox coding/calibration (required after replacing NOx sensors or pump)
Our mobile AdBlue service covers Stoke-on-Trent, Newcastle-under-Lyme, Stafford, Crewe and surrounding areas. We carry Peugeot/Citroën Diagbox and Autotuner diagnostic tools, plus common replacement parts (sensors, pumps, filters). Same-day service available. Call 07503 134 362.
Citroën Relay AdBlue problems (identical to Boxer)
The Citroën Relay shares the same platform, engine and AdBlue system as the Peugeot Boxer (and Fiat Ducato). All faults, diagnostic procedures and fixes in this guide apply equally to the Citroën Relay.
Key differences:
- Badging and trim only—mechanically identical
- Uses the same diagnostic software (Diagbox)
- Same part numbers for AdBlue components (pump, sensors, injector)
- Same fault codes and symptoms
If you’re searching for “Citroën Relay AdBlue problems,” all the information in this guide applies to your van.
“Got the dreaded P20EE on my 2017 Boxer at 72,000 miles—’AdBlue fault, 1200 km to engine shutdown,'” Mark the builder told me. “Topped up 15 litres of fresh AdBlue, drove for 30 minutes on the M6, countdown kept going down. Tried disconnecting the battery—nothing. Called you, you came out same afternoon, plugged in Diagbox, showed me the quality sensor was reading 0% even though I’d just filled the tank. Pulled the sensor out through the filler cap—absolutely caked in white crystals. Cleaned it in warm water, dried it, refitted, cleared the codes. Warning gone, countdown reset. £70 call-out instead of £250 at the dealer for a new sensor. Three months later, still perfect. Wish I’d called you first instead of wasting £30 on AdBlue and two hours driving around trying to fix it myself.”
Peugeot Boxer AdBlue Problems FAQ
What are the most common Peugeot Boxer AdBlue problems?
The most common faults are: P20EE quality sensor failures (60% of cases—reads empty when tank is full), AdBlue pump failures (60,000–100,000 miles), temperature sensor faults (P20E9), heater faults in winter (P13DF), injector blockage (short trip usage), and wiring/connector corrosion.
How do I reset the AdBlue warning on a Peugeot Boxer?
You can’t reset the warning without fixing the root cause first. Once fixed, use a diagnostic scanner to clear the fault codes. For countdown resets, you need Peugeot/Citroën Diagbox (dealer-level tools). Simply disconnecting the battery won’t reset the countdown on Euro 6 Boxers.
How much does it cost to fix Peugeot Boxer AdBlue problems?
Quality sensor cleaning: £60–£120 (mobile service)
Quality sensor replacement: £150–£320 (sensor + fitting)
AdBlue pump replacement: £400–£730 (pump + fitting + coding)
NOx sensor replacement: £360–£720 per sensor (sensor + fitting + coding)
Injector cleaning: £100–£180
Injector replacement: £330–£600
Tank drain/flush (contamination): £150–£300
Diagnostics only: £50–£80
Can I drive my Peugeot Boxer with the AdBlue warning light on?
Yes, but only until the countdown reaches zero. The warning gives you 1200 km (750 miles) to get it fixed, then reduces to 800 km, then 50 km, then the engine won’t restart. Don’t ignore it—get it diagnosed and fixed before you run out of kilometres.
Why does my Peugeot Boxer say AdBlue fault when the tank is full?
The quality sensor (level sensor) inside the AdBlue tank has failed or is covered in white crystals (dried AdBlue). The sensor reads 0% or “poor quality” even though the tank is full of fresh AdBlue. Fix: clean or replace the sensor. Cost: £60–£320 depending on whether cleaning works or you need a new sensor.
How long does AdBlue last in a Peugeot Boxer?
Depends on engine size, driving style and load. Typical consumption: 1 litre of AdBlue per 600–1,000 km. 2.0 BlueHDi (Euro 6b): 800–1,000 km per litre. 2.2 BlueHDi (Euro 6d): 600–800 km per litre (higher consumption). Heavy loads and motorway driving increase AdBlue consumption.
Where is the AdBlue tank on a Peugeot Boxer?
Under the van, driver’s side, behind the rear wheel. Tank capacity: 17 litres (2015–2022 models), 20 litres (2023+ models). Access for sensor cleaning: via the blue AdBlue filler cap (sensor is inside the filler neck). Access for pump replacement: jack up the van and remove plastic undertray.
Are Citroën Relay AdBlue problems the same as Peugeot Boxer?
Yes—the Citroën Relay and Peugeot Boxer are mechanically identical (same platform, engine, AdBlue system). All faults, diagnostic procedures and fixes are the same. They also share the same parts and diagnostic software (Diagbox).
What happens if I ignore the AdBlue warning on my Boxer?
The countdown reduces from 1200 km to 800 km to 50 km to 0 km. Once it reaches zero, the engine will not restart (you can finish your current journey, but once you turn the engine off, it won’t start again). You’ll need recovery to a garage or a mobile specialist to fix it on-site before you can drive again.
For related Peugeot Boxer and Citroën Relay AdBlue guides, see our AdBlue warning light won’t go off troubleshooting, NOx sensor cleaning guide, AdBlue in diesel tank emergency fix, or top AdBlue fault codes explained.
Peugeot Boxer or Citroën Relay AdBlue fault won’t clear?
We diagnose and fix all Peugeot Boxer and Citroën Relay AdBlue faults on-site across Stoke-on-Trent, Newcastle-under-Lyme, Stafford and Crewe. Sensor cleaning, pump replacement, code clearing and countdown resets using Diagbox tools. Same-day service available.
07503 134 362 | ✉ info@adbluespecialist.co.uk
Hours: Mon–Sun 09:00–20:00 | Average response time: 30–90 minutes
