Troubleshooting Eberspacher Airtronic D2L, D4L, and D6L Fault Code P00012A: H1 Fuel Supply
If you’re using an Eberspächer Airtronic D2L, D4L, or D6L diesel air heater and encountering the P00012A fault code, often accompanied by an H1 fuel supply displayed on the Easy Start Pro - you’re likely dealing with a failed start due to insufficient fuel delivery. This issue can be intermittent and frustrating, especially when multiple resets are needed to get the heater running.
This guide walks you through the causes, diagnostics, and solutions based on the official Eberspächer workshop manual.
🔍 What Does Fault Code P00012A Mean?
The P00012A code indicates an unsuccessful starting process, typically caused by:
- Air in the fuel line
- Blocked or restricted fuel supply
- Faulty or clogged metering pump
- Combustion air or exhaust system issues
✅ Step-by-Step Troubleshooting
1. Inspect the Fuel System
Start with a visual and physical inspection:
- Is there enough fuel in the tank?
- Are the fuel lines free of leaks or air bubbles?
- Are the hoses kinked, cracked, or improperly routed?
- Is the fuel pickup correctly installed and submerged?
Also, check the strainer inside the metering pump, which can become clogged over time.
🛠️Reset the Control Box
If the heater fails to start 10 times, it locks out. To reset:
- Switch on the heater
- Remove the fuse within 20 seconds
- Reinsert the fuse after ~5 seconds
This clears the lockout and allows another start attempt.
🛠️ Preventive Tips for Reliable Operation
- Use high-quality fuel lines to prevent air ingress.
- Install a fuel filter between the tank and pump.
- Mount the metering pump below the fuel level to reduce air bubble formation.
- Run the heater regularly, even in warmer months, to keep the fuel system primed.
Eberspacher repairers and workshops will be able to use the Eberspacher Easy Scan for further diagnostic.
Test Fuel Delivery with EasyScan
Use the EasyScan diagnostic tool to verify fuel delivery:
- Set frequency to 7 Hz
- Run for 60 seconds
- Expected fuel delivery:
- D2L: ~8.7 ml (range: 7.9–9.5 ml)
- D4L: ~8.1 ml (range: 7.3–8.9 ml)
- D6L: ~25 ml (range: 22.5–27.5 ml)
If the output is below the minimum, the metering pump may need replacement.
Purge Air from the Fuel Line (initial installation).
While there’s no dedicated purge mode, EasyScan allows you to manually activate the metering pump, which effectively purges air from the system. This is especially useful after long periods of inactivity or after fuel system maintenance.
🔧 Final Thoughts
The Eberspächer Airtronic D2L, D4L, and D6L heaters are reliable and efficient, but like any diesel system, they require a clean and consistent fuel supply. By following these steps and using the right diagnostic tools, you can resolve the P00012A fuel supply fault and restore dependable heating performance.
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