P067F

Code

Generic P — Powertrain

Cylinder 6 Glow Plug Control Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 19 EN: 37 RU: 26

AI status

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Page language: EN

Causes

Short to battery positive (B+) on cylinder 6 glow plug harness
Failed or internally shorted glow plug (cylinder 6)
Damaged wiring insulation or chafing to a power source
Corroded or loose connector at glow plug 6 or at control module
Faulty glow plug driver/relay/module inside PCM or dedicated glow control module
Blown or incorrect fuse/relay in glow plug supply circuit

Symptoms

Malfunction Indicator Lamp (MIL) / check engine light illuminated
Glow-plug indicator or preheat lamp may be on continuously or behave abnormally
Hard cold starting or longer cranking time (diesel)
Rough idle or misfire on cold start
Excessive white/grey smoke on cold start
Stored DTC P067F (Cylinder 6 Glow Plug Control Circuit High)

What to check

Retrieve and record freeze frame and live data with a scan tool; verify P067F is current and whether other glow-related codes are present
Visually inspect glow plug 6 connector, wiring harness, and nearby harness routing for damage, chafe, or signs of shorting
Check fuses and relays for the glow plug supply circuit
Measure supply voltage at the glow plug connector (with connector disconnected) and at the glow control module/PCM power input
Measure resistance of glow plug 6 and compare to other cylinders (cold, engine off)
Backprobe the control/driver pin at the PCM or glow control module while commanding glow ON and OFF to observe voltage behavior

Signal parameters

Battery supply voltage at glow plug supply: ~12–14.5 V (engine off/running respectively)
Expected control-driver voltage (when driver is off/open): ~battery voltage (~12 V)
Expected control-driver voltage (when driver is commanded ON to ground): near 0 V (grounded) or pulsed (depending on system)
Typical cold glow plug resistance: often low (0.5–2.0 Ω) — significant deviation vs other cylinders suggests plug fault
‘High’ fault triggered when measured voltage or feedback exceeds PCM threshold or is inconsistent with commanded state

Diagnostic algorithm

Verify DTC and readiness with a scan tool; note freeze frame and any related codes (e.g., multiple cylinder glow faults)
Visually inspect connector, wiring and pins at glow plug 6 for corrosion, bent pins, burnt insulation, or melted plastic. Repair any damage before further testing
Check relevant fuses and relays for the glow system; replace if faulty
With ignition off, disconnect glow plug 6 connector and measure glow plug resistance to ground. Compare to same-position plugs on other cylinders. Replace plug if resistance is abnormally low (short) or open
With connector disconnected, measure supply voltage at the connector; verify battery voltage is present when expected
Backprobe the control/driver circuit at the module while commanding glow ON/OFF with a scan tool. Expected behavior: driver pulls to ground (or pulses) when ON; when OFF the line should sit at battery voltage or float depending on design. A persistent high voltage when the driver should be low indicates short to B+ or failed driver
If wiring appears ok and glow plug tests good, check for short to B+ between the control conductor and battery positive using an ohmmeter or current clamp
If possible, swap the glow plug or driver output with another cylinder (or known-good channel) to see if the fault follows the component or stays at the channel — this isolates between harness/plug and module
If tests point to a failed glow driver inside the PCM/glow module or an internal short, replace the module/PCM per manufacturer procedures and re-check codes
After repair, clear codes and perform a cold start test and re-scan to verify the code does not return

Likely causes

Wiring short to B+ at glow plug 6 harness
Failed glow plug with abnormally low resistance (internal short)
Corroded connector causing intermittent high-voltage feedback
Faulty glow plug driver in the PCM or separate glow control module

Fault status

⚠️ Status

PCM detected high voltage/abnormal feedback on the cylinder 6 glow plug control circuit. Fault indicates wiring short to battery, faulty glow plug, or failed driver; MIL set.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 to 2.5 hours