Mercedes Sprinter AdBlue Heater Fault: Winter Fix Guide 2025

It’s November. Temperatures have dropped below freezing overnight. You start your Mercedes Sprinter, and within seconds, a warning flashes on the dashboard:

“AdBlue System Fault – Engine Will Not Restart in 800 Miles”

Your heart sinks. You’ve got deliveries to make, jobs to complete, and now your van is threatening to shut down completely. Sound familiar?

You’re not alone. Mercedes Sprinter AdBlue heater faults spike dramatically in winter, and they’re one of the most common—and frustrating—issues Sprinter owners face when temperatures drop.

In this comprehensive guide, we’ll explain exactly what causes AdBlue heater faults in winter, how to diagnose them, what your repair options are, and how to prevent your Sprinter from being stranded in the cold. Whether you’re seeing fault codes P20BA, P13DF, or just a generic AdBlue warning, this guide will give you the answers you need.

Let’s get your Sprinter back on the road.

Why Do Mercedes Sprinter AdBlue Heater Faults Happen in Winter?

AdBlue (also called Diesel Exhaust Fluid or DEF) is a urea-based solution that’s injected into your Sprinter’s exhaust system to reduce harmful nitrogen oxide (NOx) emissions. It’s stored in a separate tank, usually located under the chassis or near the fuel tank.

Here’s the problem: AdBlue freezes at -11°C (12°F).

To prevent this, Mercedes Sprinters are equipped with an AdBlue heater element inside the tank. This heater warms the fluid when temperatures drop, keeping it liquid so it can be injected into the exhaust system.

In winter, this heater is under maximum stress:

• It runs constantly in freezing temperatures
• It draws significant power from your battery
• It’s exposed to moisture, salt, and road grime
• It’s prone to corrosion and electrical faults

When the heater fails, the AdBlue freezes, the system can’t inject fluid into the exhaust, and your Sprinter triggers a fault code. If you ignore it, your van will eventually refuse to restart.

Common Winter AdBlue Heater Fault Codes on Mercedes Sprinter

If your Sprinter has an AdBlue heater fault, you’ll typically see one or more of these fault codes:

P20BA – Reductant Heater A Control Circuit/Open

What it means: The AdBlue heater element has failed or has an electrical fault (open circuit, broken wire, or corroded connector).

Symptoms: AdBlue warning light, countdown to engine shutdown, frozen AdBlue in extreme cold.

Common cause: Failed heater element (most common in winter).

P13DF – DEF Heater Incorrect Performance

What it means: The AdBlue heater is not warming the fluid properly. It may be partially working but not reaching the required temperature.

Symptoms: Slow AdBlue warming, intermittent faults, countdown warnings in very cold weather.

Common cause: Weak heater element, low battery voltage, or frozen AdBlue blocking the system.

P20E8 – Reductant Pressure Too Low

What it means: The AdBlue pump can’t build pressure, often because the fluid is frozen or the heater isn’t working.

Symptoms: AdBlue warning, countdown, rough running, reduced power.

Common cause: Frozen AdBlue due to heater failure.

P204F – Reductant System Performance

What it means: The entire AdBlue system isn’t performing correctly, often due to frozen fluid or heater malfunction.

Symptoms: Multiple AdBlue warnings, countdown, limp mode.

Common cause: Heater fault combined with frozen AdBlue.

For a complete breakdown of all Mercedes Sprinter AdBlue fault codes, see our detailed guide: Mercedes Sprinter AdBlue Fault Codes Explained.

Symptoms of a Mercedes Sprinter AdBlue Heater Fault

Here’s how you’ll know your Sprinter has an AdBlue heater fault:

1. Dashboard Warning Light

The AdBlue warning light (usually amber) will illuminate on your dashboard. It may show a wrench icon, an AdBlue symbol, or a generic engine management light.

2. Countdown Warning Messages

Your Sprinter will display countdown messages on the instrument cluster:

• “Engine Will Not Restart in 800 Miles”
• “Engine Will Not Restart in 500 Miles”
• “Engine Will Not Restart in 50 Miles”
• “Engine Will Not Restart – Refill AdBlue”

Critical: Once the countdown reaches zero, your Sprinter will not restart. You’ll be stranded until the fault is fixed.

3. Cold Start Issues

Your Sprinter may struggle to start on cold mornings, or it may start but run roughly for the first few minutes as the system tries to warm frozen AdBlue.

4. Reduced Power (Limp Mode)

In some cases, the engine will enter limp mode, limiting power to 50-60% and reducing top speed to 40-50 mph.

5. Increased AdBlue Consumption

If the heater is partially working, the system may inject more AdBlue than necessary to compensate, causing unusually high consumption.

6. Frozen AdBlue Tank

In extreme cold (below -11°C), you may hear ice cracking inside the AdBlue tank when you start the engine, or the tank may feel frozen to the touch.

What Causes AdBlue Heater Faults in Winter?

Several factors contribute to AdBlue heater failures in cold weather:

1. Failed Heater Element

Most common cause. The heater element inside the AdBlue tank burns out due to constant use, corrosion, or electrical overload. Typical lifespan: 60,000–100,000 miles.

2. Corroded Electrical Connections

The heater’s electrical connectors are exposed to road salt, moisture, and grime. Corrosion causes poor contact, preventing the heater from working.

3. Low Battery Voltage

The AdBlue heater draws significant power (10-15 amps). If your battery is weak or old, it may not supply enough voltage to run the heater, especially in cold weather when battery capacity drops.

4. Frozen AdBlue Blocking the System

If the heater fails completely, the AdBlue freezes solid. Even if you replace the heater, the frozen fluid can block pipes, pumps, and injectors, causing secondary faults.

5. Faulty AdBlue Tank

In some cases, the entire AdBlue tank (which houses the heater, pump, and level sensor) develops cracks or internal faults, requiring full replacement.

6. Software Glitches

Occasionally, the ECU incorrectly reports a heater fault even when the hardware is fine. A software update or ECU reset may resolve the issue.

How to Diagnose a Mercedes Sprinter AdBlue Heater Fault

Here’s how to confirm your Sprinter has an AdBlue heater fault:

Step 1: Read the Fault Codes

Use an OBD2 diagnostic scanner (ideally Mercedes-specific like STAR Diagnostics or Autel) to read the fault codes. Look for P20BA, P13DF, P20E8, or P204F.

Step 2: Check Battery Voltage

Measure your battery voltage with a multimeter. It should read 12.6V+ when off, and 13.5-14.5V when running. If it’s below 12V, charge or replace the battery before diagnosing further.

Step 3: Inspect Electrical Connections

Locate the AdBlue tank (usually under the chassis, driver’s side). Inspect the electrical connector for corrosion, moisture, or loose pins. Clean with electrical contact cleaner if needed.

Step 4: Test the Heater Element

Using a multimeter, measure the resistance of the heater element. It should read 1-3 ohms. If it reads infinite (open circuit), the heater has failed.

Step 5: Check for Frozen AdBlue

If temperatures have been below -11°C, tap the AdBlue tank gently. If it sounds solid or you hear ice, the fluid is frozen.

Step 6: Verify AdBlue Quality

Old or contaminated AdBlue can crystallize and block the system. If your AdBlue is more than 12 months old, drain and refill with fresh fluid.

Not confident diagnosing yourself? Our mobile specialists can perform a full diagnostic scan at your location in Stoke-on-Trent. Call 07503 134362 to book.

How to Fix a Mercedes Sprinter AdBlue Heater Fault

You have three main options for fixing an AdBlue heater fault:

Option 1: Replace the Heater Element

What it involves:

• Drain the AdBlue tank
• Remove the tank from the vehicle
• Replace the faulty heater element
• Reinstall the tank and refill with fresh AdBlue
• Clear fault codes and test

Cost: £200–£400 (parts + labor)

Time: 2–3 hours

Pros: Cheapest repair option, fixes the immediate problem

Cons: Heater may fail again in 60,000–100,000 miles, doesn’t address underlying system issues

Option 2: Replace the Entire AdBlue Tank

What it involves:

• Remove the old AdBlue tank (includes heater, pump, level sensor)
• Install a new OEM or aftermarket tank
• Connect electrical and fluid lines
• Fill with fresh AdBlue
• Clear fault codes and test

Cost: £600–£1,200 (parts + labor)

Time: 3–4 hours

Pros: Brand new system, longer lifespan, fixes multiple issues at once

Cons: Expensive, still vulnerable to future winter faults

Option 3: AdBlue System Delete (Permanent Solution)

What it involves:

• Physical removal of AdBlue tank, pump, and heater
• Installation of blanking plugs
• ECU remapping to disable AdBlue monitoring
• Clearing all fault codes
• Road test verification

Cost: £199–£299

Time: 1.5–2 hours (mobile service available)

Pros: Permanent fix, no more winter faults, improved performance and fuel economy, cheaper than replacement

Cons: Not legal for road use in the UK, voids warranty, MOT risk

For a detailed comparison of repair vs. delete, see our guide: Mercedes AdBlue Delete vs Repair.

Cost Comparison: Repair vs. Delete

Can I Drive My Sprinter With an AdBlue Heater Fault?

Short answer: Yes, but not for long.

When the AdBlue heater fault first appears, your Sprinter will display a countdown (typically 800 miles). You can continue driving during this countdown period, but:

• The countdown will decrease with every mile driven
• Once it reaches zero, your engine will not restart
• You’ll be stranded until the fault is fixed
• Ignoring the warning can cause secondary faults (frozen pipes, pump damage)

Our advice: Don’t wait until the countdown reaches zero. Book a repair or delete service as soon as the warning appears to avoid being stranded in freezing weather.

Emergency Fix: What to Do If Your Sprinter Won’t Start Due to AdBlue Heater Fault

If your countdown has reached zero and your Sprinter won’t restart, here’s what to do:

Step 1: Move to a Warm Location

If possible, tow or push your Sprinter into a heated garage or indoor space. Warming the AdBlue tank may temporarily restore function.

Step 2: Refill AdBlue (Even If Tank Isn’t Empty)

Sometimes, topping up the AdBlue tank will reset the countdown and allow one restart. This buys you time to get to a repair shop.

Step 3: Disconnect the Battery

Disconnect the battery for 15 minutes, then reconnect. This may reset the ECU and allow one emergency restart. Warning: This is a temporary fix only.

Step 4: Call for Mobile Repair or Delete Service

Our mobile specialists can come to your location and either repair the heater or delete the AdBlue system on-site. Same-day service available in Stoke-on-Trent and surrounding areas.

Emergency service: Call 07503 134362 or WhatsApp 07503 134362.

How to Prevent AdBlue Heater Faults in Winter

While heater elements will eventually fail, you can reduce the risk with these preventive measures:

1. Keep Your Battery Healthy

The AdBlue heater needs 12V+ to function. Replace your battery every 4-5 years, and check voltage regularly in winter.

2. Park in a Heated Garage

If possible, park your Sprinter indoors overnight. This reduces the load on the heater and prevents AdBlue from freezing.

3. Keep the AdBlue Tank Above 25%

A fuller tank is easier to heat than a nearly empty one. Don’t let your AdBlue level drop below 25% in winter.

4. Use Fresh, Quality AdBlue

Old or contaminated AdBlue can crystallize and block the system. Replace AdBlue every 12 months, even if the tank isn’t empty.

5. Address Warning Lights Immediately

Don’t ignore AdBlue warnings. The sooner you address a fault, the less likely you are to suffer secondary damage (frozen pipes, pump failure).

6. Consider AdBlue System Delete

If you’re tired of recurring winter faults, AdBlue system delete is a permanent solution that eliminates the heater, pump, and all related components.

Why Do So Many Sprinter Owners Choose AdBlue Delete?

After experiencing multiple winter AdBlue heater faults, many Sprinter owners opt for permanent deletion. Here’s why:

1. No More Winter Breakdowns

Once the AdBlue system is deleted, you’ll never see another heater fault, frozen tank, or countdown warning—no matter how cold it gets.

2. Lower Long-Term Costs

Heater replacement costs £200–£400 every 60,000–100,000 miles. Over the life of your Sprinter, that’s £600–£1,200+. Deletion costs £199–£299 once.

3. Improved Reliability

The AdBlue system is one of the most common failure points on modern Sprinters. Removing it eliminates a major source of downtime.

4. Better Performance and Fuel Economy

Without the restrictive AdBlue system, your Sprinter will gain 5–15 HP and improve fuel economy by 5–10%. Many owners report smoother acceleration and better throttle response.

5. Convenience

No more topping up AdBlue, no more warning lights, no more emergency repairs. Your Sprinter just works.

For more details, see our comprehensive guide: Mercedes AdBlue Removal.

Real-World Case Study: 2017 Mercedes Sprinter 314 CDI

Let’s look at a real example from one of our recent customers in Stoke-on-Trent:

Mercedes Sprinter Model-Specific Notes

AdBlue heater faults affect most Mercedes Sprinter models, but some are more prone than others:

2006–2013 Sprinters (W906, OM651 Engine)

Common issues: Early AdBlue systems with less reliable heaters, prone to corrosion
Fault codes: P20BA, P13DF, P20E8
Recommendation: High failure rate—consider deletion if out of warranty

2014–2018 Sprinters (W906 Facelift, OM651 Engine)

Common issues: Improved heaters but still prone to winter faults, especially in high-mileage vans
Fault codes: P20BA, P13DF, P204F
Recommendation: Repair if under 60,000 miles, consider deletion if higher mileage

2018+ Sprinters (W907, OM654 Engine)

Common issues: More complex AdBlue systems (AdBlue 2.0), expensive repairs, software-related faults
Fault codes: P20BA, P13DF, P20E8, P207F
Recommendation: Repair if under warranty, deletion popular for high-mileage commercial users

What Our Customers Say

“My Sprinter threw an AdBlue heater fault in the middle of a cold snap. Called AdBlue Specialist at 8am, they were at my depot by 11am, deleted the system by 1pm. Van’s been perfect ever since. Wish I’d done it sooner.”

“Third AdBlue heater failure in 5 years. Enough was enough. Had the system deleted for £250. No more warnings, better fuel economy, and I don’t have to worry about winter breakdowns anymore.”

“Mercedes wanted £900 for a new AdBlue tank. AdBlue Specialist deleted the system for £250 at my house. Saved me £650 and 2 days without my van. Brilliant service.”

Frequently Asked Questions

What causes Mercedes Sprinter AdBlue heater faults in winter?

AdBlue heater faults in winter are caused by: frozen AdBlue fluid (freezes at -11°C), faulty heater element, corroded electrical connections, low battery voltage preventing heater operation, and crystallized AdBlue blocking the system. Cold temperatures put maximum stress on the heating system.

How much does it cost to fix a Sprinter AdBlue heater fault?

Repair costs: Heater element replacement £200–£400, full tank replacement £600–£1,200, electrical repair £150–£300. AdBlue system delete costs £199–£299 and is a permanent solution that eliminates future heater faults.

Can I drive my Sprinter with an AdBlue heater fault?

Initially yes, but you’ll see countdown warnings (800 miles, 500 miles, etc.). Once the countdown reaches zero, your Sprinter will not restart. You typically have 500–800 miles before complete shutdown. Don’t ignore the warnings.

How long does AdBlue heater repair take?

Heater element replacement: 2–3 hours. Full tank replacement: 3–4 hours. AdBlue system delete: 1.5–2 hours. Mobile service available at your location in Stoke-on-Trent.

Will AdBlue heater faults happen every winter?

Yes, if the underlying issue isn’t fixed. Heater elements typically fail every 60,000–100,000 miles. Many Sprinter owners choose AdBlue delete to permanently eliminate recurring winter faults.

What is fault code P20BA on Mercedes Sprinter?

P20BA means “Reductant Heater A Control Circuit/Open”. This indicates the AdBlue heater element has failed or has an electrical fault. Common in winter when the heater is under maximum load trying to prevent AdBlue from freezing.

What is fault code P13DF on Mercedes Sprinter?

P13DF means “DEF Heater Incorrect Performance”. This indicates the AdBlue heater is not warming the fluid properly, often due to a failing heater element, low voltage, or frozen AdBlue blocking the system.

Can I prevent AdBlue heater faults in winter?

Prevention tips: Keep your Sprinter in a heated garage when possible, maintain battery health (heater needs 12V+), use quality AdBlue, don’t let the tank run below 25%, and address warning lights immediately. However, heater elements will eventually fail regardless of maintenance.

Why Choose AdBlue Specialist for Your Sprinter Winter Fix?

✅ Mobile Service – We Come to You

No need to tow your Sprinter to a garage. We’ll diagnose and fix the fault at your home, workplace, or roadside in Stoke-on-Trent and surrounding areas.

✅ Same-Day Service Available

Winter breakdowns can’t wait. We offer same-day appointments for urgent AdBlue heater faults. Call before 10am for same-day service.

✅ Expert Sprinter Specialists

We specialize in Mercedes Sprinter AdBlue systems. We’ve fixed hundreds of winter heater faults and know exactly what works.

✅ Transparent Pricing

No hidden fees. We’ll give you a clear quote before starting work, and we’ll explain all your options (repair vs. delete).

✅ 12-Month Warranty

All repairs and deletions come with a 12-month warranty for peace of mind.

✅ Honest Advice

We’ll never upsell you. If a simple fix will work, we’ll tell you. If deletion is the better long-term solution, we’ll explain why.

Service Areas

We provide mobile Mercedes Sprinter AdBlue heater fault repairs and deletions across Staffordshire:

• Stoke-on-Trent
• Stone
• Stafford
• Newcastle-under-Lyme
• Crewe
• Leek, Kidsgrove, Sandbach, Congleton, Nantwich, and surrounding areas

For a full list of service areas, visit our locations page.

Related Services

In addition to AdBlue heater fault repairs, we also offer:

• Mercedes AdBlue Delete – Permanent removal of the entire AdBlue system
• Mercedes AdBlue Removal – Complete system removal and ECU remapping
• AdBlue Repair – Pump, injector, and sensor repairs
• NOx Sensor Delete – Remove faulty NOx sensors
• Performance Remap – Increase power and torque
• Economy Remap – Improve fuel efficiency

Winter AdBlue Tips for Sprinter Owners

Here are some additional winter tips to keep your Sprinter running smoothly:

1. Check Your AdBlue Level Weekly

Don’t let your AdBlue drop below 25% in winter. A fuller tank is easier to heat and less likely to freeze completely.

2. Use a Battery Conditioner

If your Sprinter sits unused for days, connect a battery conditioner to maintain voltage. The AdBlue heater needs 12V+ to function.

3. Warm Up Your Engine Before Driving

Let your Sprinter idle for 2–3 minutes before driving in freezing temperatures. This gives the AdBlue heater time to warm the fluid.

4. Avoid Short Journeys in Extreme Cold

Short trips (under 10 minutes) don’t give the AdBlue system enough time to warm up, increasing the risk of faults.

5. Keep Emergency Contact Numbers Handy

Save our number in your phone: 07503 134362. If you get an AdBlue warning, call us immediately for advice or same-day service.

Conclusion: Don’t Let Winter AdBlue Faults Strand Your Sprinter

Mercedes Sprinter AdBlue heater faults are one of the most common—and most frustrating—winter issues for van owners. But they don’t have to leave you stranded.

Here’s what you need to remember:

• AdBlue heater faults spike in winter due to freezing temperatures and increased heater load
• Common fault codes include P20BA, P13DF, P20E8, and P204F
• You have three options: heater replacement (£200–£400), full tank replacement (£600–£1,200), or AdBlue system delete (£199–£299)
• Deletion is the most cost-effective long-term solution and eliminates future winter faults
• Don’t ignore countdown warnings—once they reach zero, your Sprinter won’t restart
• Mobile service is available for same-day repairs or deletions at your location

Whether you choose repair or deletion, the most important thing is to act quickly. The sooner you address an AdBlue heater fault, the less likely you are to suffer secondary damage or be stranded in freezing weather.

If you’re experiencing AdBlue heater faults, recurring winter warnings, or countdown messages, don’t wait until it’s too late.

Further Reading

For more information on Mercedes Sprinter AdBlue issues and solutions, check out these related guides:

• Complete Guide to Mercedes Sprinter AdBlue Fault Codes
• What to Do If Your Car Won’t Start Due to AdBlue Issues
• AdBlue Pump Fault vs Heater Fault: How to Tell the Difference
• AdBlue Consumption Too High: 5 Causes and On-Site Checks
• Mobile vs Garage AdBlue Service: Which Is Better?
• Winter AdBlue Problems: Complete Prevention Guide