U01B6
Lost Communication With Fuel Heater Control Module
ECU lost communication with fuel heater control module (heats diesel fuel to prevent waxing in cold).
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Common causes
Ordered by how often each turns out to be the cause.
- Module unpoweredCommon
- Gateway module routing CAN messages incorrectlyLess likely
- CAN terminating resistor (120 Ω) drifted out of specLess likely
Parts involved
- Fuel Heater Module
- CAN Bus
U01B6 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.