HomeTrouble CodesU0307

U0307 — Software Incompatibility Glow Plug Control Module 1

Generic OBD-II · all makesNetwork / communication

This code indicates a software mismatch between the engine control module and the glow plug control module. It prevents proper communication regarding glow plug operation, typically occurring after module replacement or incomplete programming updates. The vehicle may limit engine performance until the modules are synchronized.

Symptoms

What causes it — most likely first

1. Outdated module firmware

One or both control modules require a software update to match current calibration standards.

2. Faulty Glow Plug Control Module

Internal failure within the glow plug controller prevents proper data exchange with the engine computer.

3. Recent battery disconnect or voltage spike

Low voltage or power loss can corrupt module memory, leading to perceived software mismatches.

4. Wiring harness issues between PCM and GPCM

Damaged communication wires can corrupt data signals, mimicking a software incompatibility.

5. Poor ground connections at control modules

High resistance in module grounds disrupts stable communication required for software handshake.

6. Faulty PCM

Internal failure of the engine computer is rare and should only be considered after all other options are exhausted.

How it's diagnosed

  1. Scan all modules for related communication codes and record freeze frame data.
  2. Check for technical service bulletins regarding software updates for this code.
  3. Inspect battery voltage and charging system stability to rule out power issues.
  4. Verify wiring integrity between PCM and Glow Plug Control Module.
  5. Reprogram or update software on affected modules using appropriate tools.
  6. Replace Glow Plug Control Module if reprogramming fails to resolve the issue.

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make

Frequently asked

Does this code mean I need a new engine computer?

Rarely. This usually indicates a software update is needed or the glow plug module itself requires replacement.

Can I drive with this code?

It is not recommended, especially in cold weather, as starting performance may be compromised.

Will clearing the code fix it permanently?

No, the software incompatibility will return until the modules are properly synchronized or replaced.

Did a recent repair cause this?

Yes, replacing a module without programming it to the vehicle often triggers this code.