P2AF6: Starter Relay C Stuck Off
What to do
Nothing is being damaged, unlike the opposite version of this fault. The engine simply may not crank when asked.
The pattern to notice: bright lights and a normal dashboard, but no crank. A flat battery makes everything go dim — so a car that is fully alive and simply will not turn over points at the starter switching rather than the battery, which is useful to say when you call for help.
On a stop-start car, expect the engine to stop at a junction and not restart, or the stop-start to have quietly stopped working. That second one is the car protecting you, and it is worth investigating rather than living with.
Ask for the relay and its socket to be checked before a starter motor is quoted for. Relays in these systems are worked far harder than in older cars and are cheap; the starter is not. Many can be swapped with an identical neighbour in the fuse box as a free test.
What this code means
The third starter relay is not passing current when it has been commanded on.
This is the harmless direction of the same failure described at P2AF5, and the contrast between them is worth keeping. Stuck on destroys the starter and the ring gear. Stuck off simply means the engine does not turn — inconvenient, occasionally at the worst possible moment, and mechanically harmless.
What the driver meets is a car that is dead at the key, with everything else working. Lights bright, dashboard normal, radio playing, and a single click or no sound at all when the key is turned. That combination is diagnostic in itself: a flat battery dims everything, so bright lights with no crank points at the switching rather than at the supply.
On a stop-start vehicle it is more likely to appear as something else first. The engine stops at a junction and does not come back, or the system quietly stops stopping the engine at all — which is the vehicle protecting itself, having noticed it cannot rely on the restart. A stop-start function that has silently switched itself off is worth investigating rather than accepting.
Where the fault sits is usually the relay, and it is usually cheap. Contacts that have arced enough times become high-resistance and then open; the socket is the second suspect, since heat and vibration loosen its terminal tension. The relay's own control side is the third — the module's low-current output, its wiring and the fuse feeding the coil.
One free test worth knowing. Many of these relays are physically identical to another in the same box. Swapping it with a neighbour whose failure is obvious — a horn, a fog light — establishes in a minute whether the relay or the circuit is at fault, and costs nothing at all.
Likely causes
Start here
- Failed starter relay · easy
- Corroded relay socket · easy
- Loose relay in its socket · easy
Less common
- Open circuit in relay control wiring · moderate
- Blown fuse or failed supply · easy
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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