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DTC codes / P26xx · Computer and output circuits / P263C

P263CGlow Plug Control Driver Performance

P263C indicates that the engine control module (ECM) has detected a performance fault within the glow plug control driver circuit, meaning the driver's output does not match the commanded state or expected electrical characteristics. The ECM monitors the driver's ability to energize the glow plugs and sets this code when the circuit's behavior falls outside the programmed parameters, such as an unexpected voltage or current signature.

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

Symptoms you may notice

  • Illumination of the check engine light or glow plug warning lamp, often with no other noticeable symptoms.
  • Hard starting or extended cranking when the engine is cold, especially in low ambient temperatures.
  • Rough idle or misfire immediately after a cold start due to incomplete combustion.
  • White smoke from the exhaust during cold starts because the glow plugs are not heating properly.
  • Reduced engine performance or power in cold conditions as the ECM may limit fuel delivery to protect the engine.
  • In some vehicles, the glow plug system may be disabled entirely, leading to a no-start condition in extreme cold.

Common causes, most likely first

  1. Faulty glow plug control module or driver circuit internal failure.
  2. Damaged or corroded wiring and connectors between the control module and glow plugs.
  3. Open or shorted glow plug(s) causing the driver to exceed current limits.
  4. Poor ground connection for the glow plug control circuit.
  5. ECM software or hardware fault affecting the driver output.
  6. Aftermarket or incorrect glow plugs with resistance values outside the specified range.

How to diagnose and fix it

  1. Scan all modules for stored codes and freeze-frame data to confirm P263C is the primary fault and not a secondary code.
  2. Visually inspect the glow plug control module, wiring harness, and connectors for damage, corrosion, or loose pins.
  3. Measure the resistance of each glow plug and compare to the manufacturer's specification to identify any failed plugs.
  4. Check the power and ground supplies to the glow plug control module using a multimeter and wiring diagram.
  5. Test the driver output signal from the ECM to the control module with an oscilloscope or appropriate test lamp.
  6. If the control module is suspected, substitute with a known-good unit and retest the circuit.
  7. Clear codes and perform a road test or cold-start test to verify the repair and ensure the code does not return.

Glow Plug Driver Faults Often Misdiagnosed

  • A weak or failing battery can cause voltage drops that mimic a driver performance fault, so always load-test the battery before condemning the control module.
  • Corrosion inside the glow plug connectors is a common hidden cause that resistance tests at the plug terminals may not reveal.
  • The code can be set by a single glow plug with high resistance that draws excessive current only when cold, so testing plugs at room temperature can miss the fault.
  • On some vehicles, the glow plug control module is integrated into the ECM, making diagnosis more complex and requiring advanced scan tool capabilities.
  • After replacing glow plugs, always clear adaptive learning values in the ECM; otherwise, the old driver strategy may persist and reset the code.

Can I keep driving with P263C?

You can generally drive the vehicle with this code, but cold starting may be difficult and prolonged driving with a faulty glow plug system can lead to excessive exhaust smoke and increased engine wear. Avoid heavy load or high-speed driving until the fault is repaired, and do not rely on the vehicle for cold-weather starts.

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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