P06FC

What it means

P06FC is the generic code for a fault in the communication circuit between the powertrain control module (PCM) and glow plug control module 2. The PCM sets it when messages from the second glow plug module are missing, corrupted or out of range. Which glow plugs module 2 controls depends on the engine, for example a second bank or a second group of cylinders.

Symptoms

• Engine management warning light on, and possibly a glow plug or diesel system warning light
• Hard starting or extended cranking in cold weather
• White smoke and rough running for the first minutes after a cold start
• Rattly, uneven idle until the engine warms up
• Increased emissions or poor cold-start fuel economy
• Other glow plug or network communication codes stored alongside it

Possible causes

• Damaged, chafed or open-circuit wiring in the communication line between the PCM and glow plug control module 2likely
• Corroded, loose or water-contaminated connector at glow plug control module 2 or the PCMlikely
• Low or unstable power supply, blown fuse or poor earth at glow plug control module 2possible
• Low battery voltage or a weak charging system disrupting module communicationpossible
• Faulty glow plug control module 2 (internal failure)possible
• Outdated or faulty software in the PCM or glow plug module, where the manufacturer has identified this as a causerare
• Internal PCM fault affecting communicationrare

How to diagnose

1. Read all stored and pending codes and record the freeze frame data, noting engine temperature, battery voltage and whether other glow plug or network codes are present
2. Check battery condition and charging voltage, as low voltage can cause false communication faults
3. Locate glow plug control module 2 using the vehicle wiring diagram, as its position and the glow plugs it serves vary by model and engine
4. Inspect the module, its connector and the harness for damage, corrosion, water ingress, heat damage or rubbing
5. Check the fuse and the power and earth supplies to glow plug control module 2 under load
6. With the ignition off and the battery disconnected as the wiring diagram advises, test the communication circuit for continuity, short to earth, short to voltage and high resistance
7. Use a scan tool to check whether module 2 responds and whether live data shows its status
8. Check for manufacturer software updates or service bulletins covering the PCM and glow plug modules for that engine

How to fix

• Repair or replace the damaged communication wiring and secure it clear of heat and abrasion
• Clean, repair or replace corroded or loose connectors and terminals
• Restore the power or earth supply by repairing the wiring or replacing the blown fuse after finding why it failed
• Charge or replace a weak battery and repair any charging system fault
• Replace glow plug control module 2 once the wiring and supplies are proven good, and complete any required programming or adaptation
• Apply a manufacturer software update to the PCM or module only where a bulletin identifies it as a known cause

Can I keep driving?

Nearby codes

• P06FBGenericGlow Plug Control Module 2 Memory Checksum Error
• P06FDGenericGlow Plug Control Module 2 to PCM Communication Circuit Range/Performance