P067D — Cylinder 5 Glow Plug Control Circuit High #

The label for this trouble code may vary depending on the vehicle’s manufacturer.

• Cylinder 5 Glow Plug Control Circuit High (Generic/SAE)
• Glow Plug Circuit High – Cylinder 5 (Ford, GM, Chrysler, Mercedes-Benz)
• Cylinder 5 Glow Plug Circuit Signal Too High (Renault, Nissan)
• Cylindre 5 Circuit de préchauffage signal élevé (Peugeot, Citroën, translation)

Summary of Code P067D #

The P067D Diagnostic Trouble Code (DTC) indicates a detected issue with the glow plug control circuit for cylinder 5, specifically that the circuit voltage is higher than expected. Glow plugs are heating elements used in diesel engines to aid cold starting by warming the combustion chamber. When the Powertrain Control Module (PCM) or Engine Control Module (ECM) detects excessively high voltage or current in the cylinder 5 control circuit, it sets this code. This code is often related to electrical faults such as a short to battery voltage, wiring issues, or a malfunctioning glow plug relay. While the engine may still run, efficiency, emissions, and starting performance can be affected.

Common Symptoms for Code P067D #

A P067D code can display a range of symptoms, some subtle and some more obvious, especially during cold weather. Here’s what you might notice:

• Illuminated Check Engine Light or Glow Plug Warning Light
• Difficult or prolonged engine starting, especially in cold conditions
• Uneven idle or engine misfire during warm-up phase
• Increased exhaust smoke during startup
• Reduced engine power and performance after a cold start
• Possible DTCs for other glow plug circuits

Most Likely Causes for Code P067D #

Certain root causes are more frequent than others for a P067D code. Here’s what technicians often find, listed in order of likelihood:

1. Faulty glow plug in cylinder 5 (internal short or resistance too low)
2. Damaged wiring or connectors in the cylinder 5 glow plug circuit (short to battery voltage or corrosion)
3. Malfunctioning glow plug relay (sticking contacts or internal short)
4. Faulty glow plug control module (if equipped)
5. PCM/ECM failure (rare, but possible if all else tests good)

Step-by-Step Diagnosis for Code P067D #

A methodical approach is key to identifying the true cause of a P067D code. Here’s how a skilled technician would proceed:

1. Confirm code presence and record freeze frame data using a scan tool.
2. Visually inspect the cylinder 5 glow plug connector, wiring, and harness for damage, melting, or corrosion.
3. With ignition off, unplug the cylinder 5 glow plug and measure resistance across the glow plug terminals with a multimeter. Compare to manufacturer specs.
4. Check for voltage at the glow plug connector with ignition on (should only be present for a limited time after key-on).
5. Inspect the glow plug relay and control module (if present) for signs of arcing or internal faults.
6. If wiring and components test good, perform a continuity check from the PCM/ECM to the glow plug connector.
7. Clear the code, cycle the ignition, and observe if P067D returns.

Possible Repairs for Code P067D #

Once the underlying issue is identified, the following repairs may resolve the P067D code:

• Replace the cylinder 5 glow plug if resistance is out of spec
• Repair or replace damaged wiring or connectors in the glow plug circuit
• Replace a faulty glow plug relay
• Replace the glow plug control module if present and found faulty
• In rare cases, update or replace the PCM/ECM if internal failure is confirmed

Is It Safe to Drive With Code P067D? #

Driving with a P067D code is usually possible in the short term, especially in mild climates, but it is not recommended for extended periods or in cold weather. A malfunctioning glow plug can make starting difficult, increase emissions, and may eventually cause misfires or poor engine operation. If you notice severe starting issues or other performance problems, address the fault as soon as possible to avoid further complications.

Vehicles Most Commonly Affected by Code P067D #

This code is most prevalent in modern diesel vehicles equipped with individual glow plug monitoring. The following OEMs and models are frequently affected:

• Ford Super Duty (F-250, F-350) Power Stroke Diesel
• General Motors (Chevrolet Silverado, GMC Sierra) Duramax Diesel
• Chrysler/Dodge Ram with Cummins Diesel
• Mercedes-Benz Sprinter and Bluetec diesel engines
• Renault Master, Trafic, and Nissan NV diesel vans

Common Mistakes & Best Practices for Code P067D #

Diagnosing glow plug codes like P067D can be tricky, and certain errors are common. Avoid these pitfalls for a successful repair:

• Automatically replacing the glow plug without checking wiring/connectors
• Overlooking the relay or control module as a potential cause
• Failing to verify voltage supply and ground at the glow plug connector
• Not clearing the code after repair and confirming that it does not return
• Using non-OEM (Original Equipment Manufacturer) glow plugs that may not meet electrical specs

Quick FAQ for Code P067D #

Here are answers to some of the most common questions drivers and technicians have about code P067D:

• Q: Will a faulty glow plug damage my engine?
  A: In most cases, no serious engine damage will result from a single faulty glow plug, but repeated cold starts with poor combustion can lead to increased emissions, rough running, and potential long-term wear.
• Q: Can I replace just one glow plug, or should I do all at once?
  A: You can replace just the faulty plug, but if one has failed, others may soon follow—many technicians recommend replacing all glow plugs if vehicle mileage is high or plugs are original.