Invalid Data Received From Auxiliary Heater Module
The U0427 code means the vehicle's onboard diagnostic system has detected: Invalid Data Received From Auxiliary Heater Module. This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $300 - $1,200 (parts and labor)
Network codes mean modules are not communicating. You need a scanner that reads all systems to find the problem.
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Common Symptoms
- Auxiliary heater not warming cabin
- Webasto/Eberspacher heater error
- Pre-heater timer not working
- Diesel heater producing smoke but no heat
Probable Causes (Ranked by Likelihood)
- Failed auxiliary heater control module Very High
- Glow plug failure in auxiliary heater High
- CAN bus data error Moderate
- Fuel supply issue to heater Low
Step-by-Step Diagnostic Procedure
-
Check auxiliary heater fuel supply
-
Scan heater module for codes
-
Test glow plug resistance
-
Inspect CAN bus at heater module
Frequently Asked Questions
Can I drive with U0427?
Yes. The main heating system still works. Only the auxiliary pre-heater is affected.
What causes U0427?
Usually a failed heater module or glow plug in the auxiliary heater unit.
What is an auxiliary heater?
A fuel-burning heater that warms the cabin and engine before starting, common in European vehicles.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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