U0407

Invalid Data Received From Glow Plug Control Module

U0407 is a generic OBD-II network diagnostic trouble code: Invalid Data Received From 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
U0407
Group
Network
System
Glow
Severity
Warning (MIL on)
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What U0407 means

DTC U0407 is stored when the engine control module (ECM) receives data from the Glow Plug Control Module (GPCM) that is outside expected parameters or is flagged as invalid by the network message-validation protocol. Unlike U00xx lost-communication codes, U04xx codes indicate that communication itself is intact but the content of the received message is implausible or corrupted.

The glow plug control module on diesel vehicles manages preheating of the glow plugs for cold starts and reports glow plug status, current, and fault information to the ECM over the CAN bus. When the ECM receives invalid glow plug data, it may not be able to properly coordinate the preheat cycle, which typically affects cold-start behavior, warm-up quality, and emissions during the initial minutes of operation.

Invalid data can result from a failing GPCM generating out-of-range status messages, a wiring or connector fault causing signal corruption on the bus, electrical noise or a failing bus termination resistor altering the bit pattern, or unstable power and ground to the module. Because the GPCM requires a stable 12 V supply and a solid chassis ground, corroded battery terminals, a loose connector, or a weak fuse can interrupt its processor and produce garbled frames.

Common causes

Most-frequently reported root causes when U0407 is logged.

  • 1
    Failing Glow Plug Control Module generating out-of-range or corrupted status messages.
  • 2
    CAN bus wiring fault or failing termination resistor corrupting messages on the GPCM segment.
  • 3
    Software fault or corrupted calibration in the GPCM.
  • 4
    Corroded or loose connector at the glow plug control module producing intermittent bit errors.
  • 5
    Unstable 12 V power or poor chassis ground to the GPCM causing erratic transmissions.
  • 6
    Electrical noise or interference corrupting CAN messages in the GPCM circuit.
  • 7
    GPCM firmware incompatibility after a module replacement without proper programming.

Symptoms drivers notice

MIL illuminated, sometimes with a glow plug or preheat warning lamp.
Hard or delayed cold starting.
Rough idle or misfire until the engine warms up.
Increased white or blue smoke on cold start.
Additional glow plug system or network DTCs may be stored.

How to diagnose U0407

A typical diagnostic flow when this code is present.

  1. 1
    Read all DTCs and note all glow plug system and network codes.
  2. 2
    Verify CAN bus integrity and check whether other modules report communication issues.
  3. 3
    Inspect the GPCM harness and connector for corrosion or wiring damage.
  4. 4
    Check GPCM power and ground supply circuits for proper voltage and low resistance.
  5. 5
    Monitor GPCM live data PIDs to evaluate the quality of the data being transmitted.
  6. 6
    Check for available GPCM software updates or reflash if a known firmware issue exists.
  7. 7
    Replace the GPCM only after confirming wiring, power supply, and bus integrity.

Related network codes

Frequently asked questions

What is the difference between U0407 and U0100 series codes?

U04xx codes indicate invalid data content received from a module, while U01xx codes indicate the communication link itself is absent. The glow plug module is communicating in U0407, but its data is not trusted.

Will U0407 leave me stranded?

Usually not, but it can make cold starting difficult and cause rough running until the engine warms, so it should be addressed promptly in cold climates.

Does the glow plug control module need programming after replacement?

On many modern diesels the replacement module must be programmed or configured to match the vehicle to avoid communication and calibration mismatches.

Can a bad CAN bus terminator cause U0407?

Yes. A failing termination resistor or bus integrity fault can corrupt messages and trigger U04xx codes, so verify bus termination before focusing on the module itself.

Disabling U0407 in software

RaceTune can permanently disable U0407 — 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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