Failed glow plug on cylinder 12 (open heating element or internal short); Damaged or corroded glow plug electrical connector at cylinder 12; Chafed, pinched, or broken wire in the glow plug control circuit to cylinder 12; Faulty glow plug control module (GPCM) or relay output for that cylinder; Poor ground connection shared by the glow plug circuit; Corrosion or water intrusion in the glow plug harness connector; Rarely, an internal ECM driver fault on the glow plug control circuit

DTC codes / P06xx · Computer and output circuits / P06E2

P06E2Cylinder 12 Glow Plug Control Circuit Low

Q: What does code P06E2 mean?

Cylinder 12 Glow Plug Control Circuit Low. P06E2 means the engine control module (ECM) has detected an abnormally low voltage on the control circuit for cylinder 12's glow plug, indicating a short to ground, an open circuit, or a failed glow plug. The ECM commands the glow plug on and monitors the circuit's electrical behavior; when the feedback signal stays below the expected threshold, it stores this code and may disable glow plug operation for that cylinder.

P06E2 means the engine control module (ECM) has detected an abnormally low voltage on the control circuit for cylinder 12's glow plug, indicating a short to ground, an open circuit, or a failed glow plug. The ECM commands the glow plug on and monitors the circuit's electrical behavior; when the feedback signal stays below the expected threshold, it stores this code and may disable glow plug operation for that cylinder.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaComputer and output circuits

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Hard cold starting or extended cranking before the engine fires
Rough idle and white smoke from the exhaust immediately after a cold start
Misfire or hesitation during the first few minutes of engine operation
Increased fuel consumption during warm-up
In severe cases, a no-start condition in cold weather

Common causes, most likely first

Failed glow plug on cylinder 12 (open heating element or internal short)
Damaged or corroded glow plug electrical connector at cylinder 12
Chafed, pinched, or broken wire in the glow plug control circuit to cylinder 12
Faulty glow plug control module (GPCM) or relay output for that cylinder
Poor ground connection shared by the glow plug circuit
Corrosion or water intrusion in the glow plug harness connector
Rarely, an internal ECM driver fault on the glow plug control circuit

How to diagnose and fix it

Scan all modules and record freeze-frame data to confirm P06E2 is the only glow plug code present
Visually inspect the cylinder 12 glow plug connector and harness for corrosion, chafing, or looseness
Measure the glow plug resistance at the connector and compare it to the manufacturer's specification
Check the control circuit for a short to ground and for continuity from the GPCM to the glow plug
Test the glow plug control module output for cylinder 12 with a suitable load or oscilloscope
Replace the faulty glow plug or repair the damaged wiring as indicated by test results
Clear the code, perform a cold-start relearn if required, and verify the repair with a road test

Glow Plug Circuit Low-Voltage Traps

A glow plug that tests good on a bench can still set this code if the connector terminal has spread or corroded, creating resistance that the ECM interprets as a low-voltage fault.
Technicians often replace the glow plug first, but a shorted glow plug control module output can mimic a failed plug and will destroy a new plug if not diagnosed.
This code can be set by a poor engine ground even when the glow plug and its wiring test perfectly, so ground integrity must be verified before condemning parts.
On engines with a glow plug control module, a single low circuit code for one cylinder does not always mean the plug is bad; the module's internal driver for that channel can fail independently.
P06E2 is often accompanied by other glow plug codes, and diagnosing only the first code stored can lead to repeat repairs if the shared harness or module is the real cause.

Can I keep driving with P06E2?

You can generally drive the vehicle, but cold starting will be harder and the engine may run rough or smoke until warm; avoid heavy load or long idling until the fault is repaired, and do not rely on the vehicle for cold-weather starts.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.