U0307

Software Incompatibility with Glow Plug Control Module

U0307 is a generic OBD-II network diagnostic trouble code: Software Incompatibility with Glow Plug Control Module. It is logged by the engine control unit when the glow monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
U0307
Group
Network
System
Glow
Severity
Warning (MIL on, possible limp mode)
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What U0307 means

U0307 indicates that the controlling module has detected a software incompatibility condition with the Fuel Pump Control Module (FPCM). Unlike most U-codes that signal a complete loss of communication, U0307 is specifically set when modules are able to exchange messages but the software versions or calibration levels are mismatched, preventing correct cooperative operation.

This code most commonly appears after a module replacement or software update where the new FPCM calibration does not match the rest of the powertrain network. It can also arise if a module was incorrectly programmed, flashed with a wrong software level, or if the VIN or variant coding stored in the module does not match the vehicle configuration.

Because the fuel pump control strategy may be compromised, the engine may run at reduced power or fall back to a default fuel delivery strategy. Diagnosis should focus on verifying part numbers and software versions using OEM calibration tools, confirming VIN coding, and re-flashing the FPCM with the correct software level for the vehicle rather than replacing hardware.

Common causes

Most-frequently reported root causes when U0307 is logged.

  • 1
    FPCM replaced with a unit carrying incompatible software or calibration.
  • 2
    FPCM incorrectly programmed or flashed with the wrong software version.
  • 3
    VIN coding not performed after FPCM replacement.
  • 4
    ECM updated to a new software level that the existing FPCM cannot support.
  • 5
    Counterfeit or aftermarket FPCM with non-OEM firmware.
  • 6
    Module variant configuration mismatch stored in the FPCM memory.

Symptoms drivers notice

MIL illuminated with U0307 stored in the ECM.
Engine may run in a default or reduced-power fuel delivery mode.
Fuel pump behavior may be erratic or default to a fixed duty cycle.
Other powertrain DTCs may be present due to abnormal fuel pressure.
No-start or hard-start condition in severe cases.

How to diagnose U0307

A typical diagnostic flow when this code is present.

  1. 1
    Read and record all DTCs with a scan tool before any repairs.
  2. 2
    Check the FPCM software version and part number using OEM diagnostic software.
  3. 3
    Compare the installed FPCM software level against the OEM-specified calibration for this vehicle VIN.
  4. 4
    Verify VIN coding and variant configuration are correctly stored in the FPCM.
  5. 5
    Re-flash or reprogram the FPCM with the correct OEM-approved software if a mismatch is confirmed.
  6. 6
    Clear codes and verify with a test drive that U0307 does not return.
  7. 7
    If software update does not resolve the fault, confirm the FPCM hardware part number is appropriate for the vehicle.

Related network codes

Frequently asked questions

Is U0307 a wiring problem?

Not usually. U0307 specifically flags a software incompatibility, not a communication loss; wiring faults typically produce U0100-series lost-communication codes instead.

Can U0307 appear after an ECM update?

Yes. If the ECM is updated to a software level that expects a newer FPCM calibration, U0307 can set until the FPCM is also updated.

Will clearing the code fix U0307?

No. The code will return at the next power cycle if the underlying software incompatibility is not corrected through reprogramming.

Can an aftermarket fuel pump controller trigger U0307?

Yes. Non-OEM controllers with non-standard firmware are a common cause, as they do not broadcast the expected software version identifiers.

Disabling U0307 in software

RaceTune can permanently disable U0307 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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