P067F — Cylinder 6 Glow Plug Control Circuit High

OBD2 code P067F flags a problem with the diesel glow plug system (cylinder 6 glow plug control circuit high). The car is usually drivable while you plan the repair. Common culprits: faulty glow plug relay or control module, corroded glow plug connectors, burned-out glow plug.

powertrain (engine/transmission)

Is it safe to drive?

Short-term driving is OK Safe to drive once the engine is started and warmed up. The main risk is cold-weather starting: with several dead plugs the engine may not start on a cold morning. Fix before winter.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P067F is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the diesel glow plug system for damage, corrosion, chafing or poor contact.
Subsystem check With the cylinder 6 glow plug control disconnected, measure signal voltage at the harness connector: a high reading with the component unplugged indicates a short to power in the harness; if it drops to normal, the component itself is faulty.
Subsystem check Measure resistance of each glow plug — an open plug reads infinite resistance.
Subsystem check Check voltage at the glow plug rail during the pre-glow phase.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P067F does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P067F (parts and labor, USD, independent shop rates): Replace the glow plug relay/module: $150–$450; Replace one glow plug: $80–$200; Replace a full set of glow plugs: $250–$600. Overall, fixing P067F usually costs between $80 and $600. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

How do I diagnose P067F myself?

Start with a scan: confirm P067F, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the cylinder 6 glow plug control, and verify the suspect component against live data before buying parts.

What does OBD2 code P067F mean?

How much does it cost to fix P067F?

Replace the glow plug relay/module — $150–$450; Replace one glow plug — $80–$200; Replace a full set of glow plugs — $250–$600. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

Is it safe to drive with P067F?

Safe to drive once the engine is started and warmed up. The main risk is cold-weather starting: with several dead plugs the engine may not start on a cold morning. Fix before winter.

What is the most common cause of P067F?

The most common causes are: faulty glow plug relay or control module, corroded glow plug connectors, burned-out glow plug.

When your vehicle's computer detects a problem with the glow plug system for cylinder 6, it logs trouble code P067F. This specific code appears in diesel-powered vehicles and indicates that the control circuit for cylinder 6's glow plug is reading a voltage higher than it should be — essentially a "circuit high" condition. The engine control unit (ECU) monitors this circuit closely because glow plugs play a critical role in starting a diesel engine, especially in colder temperatures.

Diesel engines rely on glow plugs to heat the combustion chamber before and during startup. Each cylinder has its own heating element threaded into the cylinder head. The ECU energizes these plugs briefly when you turn the key, and for cylinder 6 it does this through a dedicated control circuit. Normally that circuit drops to near-ground voltage when activated. When the ECU sees battery-level voltage on that signal line instead, it knows something is wrong and sets P067F.

To trigger this code, the ECU needs to see the abnormal voltage reading persist across multiple drive cycles. It also records a freeze frame snapshot capturing engine RPM, load, coolant temperature, and vehicle speed at the exact moment the fault occurred. That snapshot is gold when you're trying to reproduce the problem during diagnosis.

Typical Symptoms You'll Notice

P067F affects how your diesel starts and runs, particularly when temperatures drop:

Hard starting or no-start condition in cold weather
Check Engine Light illuminated on the dashboard
Glow plug warning light stays on after startup
White or gray exhaust smoke at startup that clears as the engine warms
Rough idle and noticeable misfire until operating temperature is reached

Most Common Culprits Behind This Code

Several issues can push the cylinder 6 glow plug circuit high. Here they are ranked from most to least frequent:

Faulty cylinder 6 glow plug with internal short pulling the signal high
Signal wire from the ECU to cylinder 6 shorted to battery positive (12V)
Open ground return path for the cylinder 6 glow plug control circuit
Burned-out or open-circuited glow plug in cylinder 6
Blown fuse protecting the glow plug control circuit
Failed glow plug relay, module, or ECU output stage
Damaged wiring insulation or corroded connectors in the glow plug harness

Step-by-Step Diagnostic Approach

Follow this logical sequence to pinpoint the failure without replacing parts unnecessarily:

Plug in an OBD2 scanner, verify P067F is stored, and record the freeze frame data — this tells you exactly what conditions triggered the fault.
Scan for any other stored codes. Related faults often point to the root cause. Also search for TSBs (technical service bulletins) specific to your make, model, and year.
Physically inspect the wiring and connectors at cylinder 6's glow plug and along the full harness route. Look for chafed wires, melted insulation, moisture intrusion, or corrosion.
Disconnect the cylinder 6 glow plug and measure voltage at the harness side of the connector. Battery voltage present with the plug unplugged means the harness itself has a short to power. Voltage dropping to normal range means the glow plug is the culprit.
Test each glow plug's resistance with a multimeter. A healthy plug reads 1–2 ohms; infinite resistance indicates a burned-out element.
Verify proper voltage delivery at the glow plug bus bar during the pre-glow sequence using a DVOM.
Clear P067F, complete a drive cycle that replicates the freeze frame conditions, and confirm the code does not return.

Repair Options and What They Cost

Once you've isolated the problem, the fix depends on which part failed:

Glow plug relay or control module replacement: $150–$450
Single glow plug replacement (cylinder 6 only): $80–$200
Complete glow plug set replacement (all cylinders): $250–$600

The Bottom Line on Driving Safely

Your diesel will start and run normally once the engine is warmed up. The glow plug system only matters during cold starts, so P067F primarily creates hard-starting issues. If only cylinder 6 is affected, the remaining plugs can usually compensate. However, if multiple plugs have failed, you risk being stranded on a cold morning. Have this repaired before winter arrives — the severity level for P067F is short: address it soon.