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P0603 fault code: what it means

P0603: PCM keep-alive memory error. Often after battery disconnection; if it returns the PCM may be faulty.

Engine and gearbox (powertrain) · Minor

Usual causes, most likely first

  1. battery disconnected or flat
  2. PCM back-up supply fault
  3. PCM

P0603 by make

Honda

PCM keep-alive memory error. Often after battery disconnection; if it returns the PCM may be faulty.

Usual causes: battery disconnected or flat; PCM back-up supply fault; PCM

Nissan

ECM keep-alive memory or power supply fault (often after battery disconnection). Learned values are lost; if it returns the ECM may need replacing.

Usual causes: ECM back-up power supply circuit open or shorted; battery recently disconnected or flat; ECM fault

Suzuki

ECM keep-alive memory error. Often after battery disconnection; recheck after clearing.

Usual causes: battery disconnected or flat; ECM back-up supply; ECM

Volvo

Engine computer keep-alive memory error. Often after battery problems.

Usual causes: low or disconnected battery; engine computer fault

Not sure what P0603 means on your car? Ask Credov.

Before you clear it

Write the code down or photograph the scanner first. A code that comes straight back after clearing points to a fault that is still there. A car whose codes were cleared just before you arrived may be hiding one: the scanner's readiness monitors show "not ready" for a while after codes are cleared.

Researched by Credov from manufacturer and workshop sources. A fault code points to where a fault may be; a workshop confirms it with a diagnosis. Browse all fault codes.