Powertrain, generic (extended)

P2AF4 Starter Relay C Control Circuit High

Check engine lightOn
EmissionsNot relevant
Drive cycleRequired
Limp modeNo

P2AF4 points to a control wire of starter relay C that carries battery voltage when the module has switched its driver off, typically because it touches a 12 V feed or because the driver leaks. With supply-side switching that can keep the coil energised; with ground-side switching the module can no longer pull the relay in. No manufacturer publishes P2AF4. Relay C is known as Starter Relay 3 at Stellantis, the relay that isolates the auxiliary battery during stop-start restarts, but its published cases concern the stuck codes P2AF5 and P2AF6 only. As a reference, GM checks the tandem starter pinion relay (P26E6) with the driver off for a short toward supply, at 0.5 Ω or less to supply, 40 failures in 50 samples, Type B over two trips. Ground and open faults are P2AF3 and P2AF2.

Likely causes

Control wire shorted to a 12 V circuit
Leaking or failed output driver
Water in the relay socket or power distribution box

Symptoms

  • Stop-start disabled
  • Relay may stay engaged with ignition off
  • Warning lamp depending on manufacturer

Repair estimate

DifficultyMediumDIY possible
Parts and labour€20–400
Time0.3–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

starter relay cwiring harnessecm

Related codes

P2AF2P2AF3P2AF5P2AF9P0617P26E6

References: law.cornell.edu, gsi.ext.gm.com, static.nhtsa.gov.