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DTC codes / P06xx · Computer and output circuits / P06FA

P06FAGlow Plug Control Module 2 Performance

P06FA indicates that the powertrain control module has detected a performance fault in the glow plug control module responsible for a second bank or circuit of glow plugs. The computer monitors glow plug activation, current draw, and timing, and it sets this code when the module's response does not match the commanded glow strategy within the expected time or current window.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaComputer and output circuits

Symptoms you may notice

  • Illuminated check engine light or glow plug warning lamp, often with no other symptoms
  • Hard cold starting or extended cranking before the engine fires
  • Rough idle and white smoke from the exhaust immediately after a cold start
  • Reduced fuel economy during warm-up and the first few minutes of driving
  • In rare cases, a no-start condition when ambient temperatures are well below freezing

Common causes, most likely first

  1. Faulty glow plug control module 2, including internal relay or driver failure
  2. Open or high-resistance wiring between the control module and the glow plugs
  3. Corroded, loose, or damaged glow plug connector terminals at the cylinder head
  4. One or more failed glow plugs drawing no current or shorting to ground
  5. Blown fuse or fusible link supplying power to the glow plug control module
  6. Poor ground connection for the control module or engine block
  7. Controller software or calibration issue requiring a reflash, though less common

How to diagnose and fix it

  1. Scan all modules for stored and pending codes, and record freeze-frame data for P06FA before clearing anything
  2. Inspect the glow plug control module 2 fuse, power feed, and ground connections for corrosion or looseness
  3. Measure resistance of each glow plug on the affected circuit and compare against the manufacturer's specification
  4. Check the wiring harness from the control module to each glow plug for opens, chafing, and high resistance
  5. Command glow plug activation with a scan tool and observe current draw and voltage drop across the circuit
  6. If the module commands correctly but current is absent or erratic, replace the glow plug control module 2 and clear codes
  7. After repair, perform a cold-start verification and confirm the code does not return over several drive cycles

What a glow plug performance code really means

  • A performance code does not automatically condemn the control module; a single weak glow plug can skew the current signature enough to trigger P06FA.
  • Technicians often overlook voltage drop on the ground side, which can mimic an internal module failure and lead to an unnecessary replacement.
  • The code can set intermittently from a harness rubbed through near the engine mount or exhaust manifold, so a wiggle test while monitoring live data is valuable.
  • Some vehicles set P06FA after a battery replacement or low-voltage event, and the code may not return once the module is reinitialized.
  • Glow plug control module 2 may share a communication bus with other modules, so a related communication code should be resolved before condemning the glow plug circuit.

Can I keep driving with P06FA?

You can generally drive the vehicle, but cold starting will be harder and the engine may run rough and smoke until warm. Avoid repeated long cranking and fix the fault before winter temperatures drop, because a failed glow plug circuit can leave you stranded in freezing weather.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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