P067F — Cylinder 6 Glow Plug Control Circuit High #

Note: The code label may vary depending on the vehicle manufacturer.

• Cylinder 6 Glow Plug Control Circuit High (Ford)
• Cylinder 6 Glow Plug Circuit High (GM/Chevrolet)
• Glow Plug Control Circuit High – Cylinder 6 (RAM/Dodge)

Summary of DTC P067F #

The P067F diagnostic trouble code (DTC) indicates that the Engine Control Module (ECM)—sometimes called the Powertrain Control Module (PCM)—has detected a voltage level that is higher than the expected range in the glow plug control circuit for cylinder 6. Glow plugs are electrical heating devices installed in diesel engines to help start the engine, especially in cold weather. The control circuit manages the electrical current sent to each glow plug. If the circuit for cylinder 6 is reporting a high voltage, it suggests a malfunction, such as an open circuit, faulty glow plug, or wiring issue. This code is most often found in modern diesel vehicles equipped with onboard diagnostics (OBD-II/EOBD).

Common Symptoms for DTC P067F #

When the P067F code is stored, drivers or technicians may notice one or more of the following symptoms. While some symptoms can be subtle, others may be more pronounced, especially during cold starts. Common symptoms include:

• Hard starting, especially in cold weather
• Rough engine idle after starting
• Illuminated check engine light (MIL – Malfunction Indicator Lamp)
• Engine misfire on cylinder 6
• Increased white smoke from exhaust during startup
• Reduced engine performance in extreme cases

Probable Causes for DTC P067F #

The causes of a P067F code typically revolve around electrical issues within the glow plug circuit for cylinder 6. Based on frequency and likelihood, the most common causes are:

1. Faulty glow plug in cylinder 6 (open circuit inside the plug or excessive resistance)
2. Damaged or corroded wiring/connectors leading to cylinder 6 glow plug
3. Defective glow plug control module (the relay or controller that manages power to each plug)
4. Blown fuse or poor electrical ground in the glow plug circuit
5. Faulty Engine Control Module (ECM/PCM) (rare, usually after all other causes are ruled out)

Step-by-Step Diagnostic for DTC P067F #

Proper diagnosis of P067F is essential before replacing parts. Here’s a recommended step-by-step approach:

• 1. Scan for additional codes: Check if other glow plug codes are present, which may indicate a broader issue.
• 2. Inspect visible wiring and connectors: Look for damage, corrosion, or loose connections specifically at cylinder 6 glow plug and control module.
• 3. Test the cylinder 6 glow plug: Using a multimeter, measure the resistance of the glow plug. Most OEMs specify between 0.5–2 ohms; a reading outside this range suggests a faulty plug.
• 4. Check for proper voltage supply: With the ignition on, use a test light or voltmeter to verify power is reaching the glow plug connector during the pre-glow cycle.
• 5. Inspect the glow plug control module/relay: Verify it is sending the correct voltage to cylinder 6 and operating as intended.
• 6. Inspect fuses and grounds: Verify the glow plug fuse is intact and all related grounds are clean and secure.
• 7. ECM/PCM check (last resort): If all components test good, suspect a control module issue or wiring fault between the ECM and the glow plug control module.

Possible Repairs for DTC P067F #

Once the source is confirmed, repairs for a P067F code typically involve addressing the faulty component or correcting the wiring. Common repair actions include:

• Replace cylinder 6 glow plug if resistance is out of specification
• Repair or replace damaged wiring/connectors in the circuit
• Replace glow plug control module or relay if faulty
• Replace blown fuse; clean and secure all related grounds
• Replace or reprogram ECM/PCM if confirmed defective (rare)

Is It Safe to Drive with Code P067F? #

Limited — Caution Advised: While the vehicle will often run with a single glow plug circuit fault, starting may be difficult, especially in cold conditions. Extended cranking can strain the battery and starter. If left unresolved, unburned fuel can cause engine misfire and increased emissions. It’s safe for short distances in mild weather, but prompt repair is strongly recommended to avoid further issues and ensure reliable starting.

Vehicles Most Commonly Affected by DTC P067F #

This code is most frequently observed in modern diesel vehicles from various manufacturers. The following models are commonly affected:

• Ford F-Series Super Duty (Powerstroke diesel engines)
• Chevrolet Silverado/GMC Sierra (Duramax diesel engines)
• Dodge RAM (Cummins diesel engines)
• Volkswagen/Audi TDI models
• Mercedes-Benz Sprinter and other BlueTEC diesels

Frequent Mistakes & Best Practices for DTC P067F #

Avoiding unnecessary part replacements and ensuring a thorough diagnosis are crucial. Here’s what to watch out for:

• Replacing the glow plug without testing it first (always measure resistance before replacement)
• Overlooking corroded connectors or ground points
• Not checking the glow plug control module when multiple glow plug codes are present
• Ignoring additional related DTCs that could indicate a broader issue
• Best practice: Always clear codes after repairs and confirm proper operation with a cold start test

Quick FAQ for DTC P067F #

Q: Can a faulty glow plug cause permanent engine damage?
A: Not directly, but repeated hard starting and misfiring can lead to increased wear and higher emissions if left unresolved.

Q: Do all diesel engines use glow plugs?
A: Most modern light-duty diesel engines use glow plugs, but some heavy-duty engines use intake heaters or other starting aids instead.