P2AF4 — Starter Relay C Control Circuit High

P2AF4: Starter Relay C Control Circuit High — what it means, the affected system and what to check before replacing parts.

Meaning, symptoms, causes and checks

Starter Relay C Control Circuit High. Basic catalogue definition; diagnostic details have not yet been reviewed.

Affected system: Powertrain

Symptoms

  • Warning light may illuminate
  • Related system function may be impaired
  • Vehicle-specific symptoms vary

Possible causes

  • Low or unstable supply voltage, fuse or relay fault, poor ground, or wiring damage
  • Related wiring, connector, power or ground fault
  • Vehicle-specific mechanical or control issue

What to check

  • Record stored and pending codes and freeze-frame data
  • Measure battery and charging voltage under load and compare with scan data; test the named circuit, fuse, relay, grounds and connectors.
  • Confirm measured values against the vehicle service information
  • Retest under the conditions that set the code
  • Measure battery and charging voltage under load and compare with scan data; test the named circuit, fuse, relay, grounds and connectors.
  • Repair the verified cause and confirm the code does not return

Also written as: P2AF4-00, P2AF400 (some scan tools add the fault-type byte, e.g. -00).