P2AF3: Starter Relay C Control Circuit Low

P2AF3 sets when the control line of starter relay C is pulled toward ground at a moment the module expects a different level. What that does to the relay depends on the driver type: with ground-side switching the short acts like a permanent on command, with supply-side switching the coil never gets current. No manufacturer publishes a set condition for P2AF3. Stellantis uses relay C as Starter Relay 3, the battery isolation relay of its stop-start Jeep and RAM models, where an energised coil splits the two batteries; only the stuck codes of that relay appear in its bulletins. GM's comparable short-to-ground test on the tandem starter pinion relay (P26E5) looks for 0.5 Ω or less to ground with 8 failures in 10 samples, Type B. Open and short-to-voltage faults are P2AF2 and P2AF4.

Medium severity. Can I keep driving?If it starts normally you can keep driving, but avoid stopping anywhere you could not get help, because it might not restart.

Symptoms

Stop-start inoperative
Relay energised all the time or not at all, depending on circuit design
Possible no-crank

Most likely causes

Control wire chafed through to ground
Shorted relay coil
Faulty output driver in the control module

What to check, in order

Start with the simplest. You can tick off each step.

Check the battery voltage
With the connector unplugged, check whether the signal wire is making contact with ground.
Try another key, if you have one
Check the fuses and the starter relay
Check the wiring and the signal to the starter motor

Good to know

Repair difficulty: medium

What each character of P2AF3 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
A: Hybrid or air and fuel
F3: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2AF3?

If it starts normally you can keep driving, but avoid stopping anywhere you could not get help, because it might not restart.

What causes code P2AF3?

The most common causes are: control wire chafed through to ground; shorted relay coil; faulty output driver in the control module.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.