P2674

Glow Plug Control Module Control Circuit Low - Bank 2

P2674 is a generic OBD-II powertrain diagnostic trouble code: Glow Plug Control Module Control Circuit Low - Bank 2. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P2674
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P2674 means

P2674 indicates that the PCM has detected a low voltage condition on the control circuit used to command the glow plug control module for bank 2. This control circuit is a low-current signal line from the PCM to the glow plug module that tells the module when and how long to energize the glow plugs.

A low condition on this circuit typically results from a short to ground on the control signal wire, an open in the return path, or an internal fault inside the glow plug control module pulling the line low. The PCM monitors the voltage on this line and sets the code when it detects the signal is stuck at or near ground potential outside of a commanded low state.

The practical effect is that the glow plug module may not receive proper commands from the PCM, leading to glow plugs that do not heat on cold starts. This manifests as difficult cold starting, white smoke, and rough running until the engine reaches operating temperature. The fault should be diagnosed promptly to avoid cold-weather starting problems.

Common causes

Most-frequently reported root causes when P2674 is logged.

  • 1
    Short to ground on the PCM-to-glow plug module control signal wire for bank 2.
  • 2
    Damaged or chafed wiring harness contacting the vehicle body or chassis ground.
  • 3
    Failed glow plug control module with an internal short on the control input.
  • 4
    Corroded connector pins at the glow plug module harness plug.
  • 5
    PCM output driver failure causing it to hold the signal low.
  • 6
    Incorrect aftermarket wiring modification creating an unintended ground path.

Symptoms drivers notice

MIL and glow plug warning light on.
Difficult cold starting in low ambient temperatures.
White or gray exhaust smoke on cold start.
Rough engine idle during warm-up.
Possible increase in cold-start emissions.

How to diagnose P2674

A typical diagnostic flow when this code is present.

  1. 1
    Scan for all DTCs and note any related glow plug or control module codes.
  2. 2
    Locate the control signal wire between the PCM and bank 2 glow plug module using the wiring diagram.
  3. 3
    Disconnect the glow plug control module connector and measure voltage on the control signal pin; it should be near supply voltage with the module disconnected if no short exists.
  4. 4
    If voltage is low with module disconnected, trace the wire back to the PCM for a short to ground.
  5. 5
    Inspect connector pins at both the module and PCM ends for corrosion or pushed-back terminals.
  6. 6
    If wiring checks out, suspect the glow plug control module and replace it.
  7. 7
    Clear DTCs, perform a cold-start test cycle, and recheck for faults.

Related powertrain codes

Frequently asked questions

Can P2674 and P2673 appear together?

Yes. Both codes relate to the bank 2 glow plug circuit and can be triggered by the same wiring or module fault. Diagnose the root cause before replacing parts.

Is the glow plug module easy to replace?

Accessibility varies by vehicle. On many modern diesels the module is mounted near the valve cover or intake manifold. Check your service manual for the exact location and procedure.

Will clearing the code fix the problem temporarily?

No. If a wiring fault or failed module is present, the code will return immediately or on the next cold start. Clearing without repair offers no lasting benefit.

Does this code affect emissions test results?

Potentially yes. If the glow plugs are not functioning properly, elevated HC emissions on a cold start could cause a failure on an emissions inspection.

Disabling P2674 in software

RaceTune can permanently disable P2674 — 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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