P2AF5 — Starter Relay C Stuck On

P2AF5: Starter Relay C Stuck On — what it means, the affected system and what to check before replacing parts.

Meaning, symptoms, causes and checks

Starter Relay C Stuck On. Basic catalogue definition; diagnostic details have not yet been reviewed.

Affected system: Powertrain

Symptoms

  • In certain FCA two-battery Start/Stop systems, ESS may be unavailable and the engine may fail to crank; this does not establish applicability to other brands.

Possible causes

  • For the FCA 'Starter Relay 3 Stuck On' interpretation, suspect an unexpected main/auxiliary battery voltage relationship or a fault in the battery power-control path.
  • Depleted auxiliary battery and power-distribution/connections can mimic a relay failure on affected FCA calibrations; relay replacement without confirmation is not justified.

What to check

  • First verify vehicle and OEM nomenclature: FCA calls this relay '3', while this generic catalogue record calls it 'C'; do not assume equivalence outside the identified vehicle.
  • Read P2AF5 and related P00FD/P2AF6 and assess both battery voltages, battery condition and the vehicle-specific power control circuit.
  • Using the FCA wiring/service procedure, inspect battery B+ connections, power-distribution fuses/connectors and power-control relay operation.
  • Check for applicable FCA service guidance about false relay DTCs with a depleted auxiliary battery before replacing parts.
  • Repair only confirmed electrical faults; verify Stop/Start and starting behavior under the manufacturer's prescribed conditions.

Also written as: P2AF5-00, P2AF500 (some scan tools add the fault-type byte, e.g. -00).