A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.
Possible causes
- The engine ground is loose or corroded
- The wiring harness has chafed on the alternator bracket or an A/C line
- CAN bus connector or wire
- Low voltage: a flat battery or corroded terminals
- The control unit itself
What you can do yourself
- The dashboard may not show the gear, and the car may not move off or engage a gear. Park only on level ground and apply the parking brake.
- Check the battery and terminals: at low voltage control units lose communication.
- Check the engine ground: the ground strap is tight on the engine and on the body, with no corrosion. Per a GM bulletin, a loose ground sets many communication codes at once.
- Inspect the wiring harness by and under the alternator: per a GM bulletin it chafes on the alternator bracket.
- Look at the codes of the other units: if communication is lost with several units at once, look for a common cause (ground, power, bus wire) rather than replacing units.
Stop and don’t drive on if:
- The Check Engine light is flashing
- The temperature gauge is in the red or the overheating light is on
- The red oil pressure light is on
- Smoke from under the bonnet, a burning or petrol smell
- Strong jerking, knocking from the engine, or the car barely moves
OOleg’s tip: check the connector
Often the cause is simple — there is no contact in the connector (plug). Look at the connector from the back: remove the rubber seal and you will see whether a wire is corroded or has come off completely. Corrosion shows up as green deposits. Ideally, gently pull each wire towards you one at a time: a sound wire stays in place, while a corroded one simply comes off — it needs to be repaired.
Unplug and inspect connectors with the ignition off.
This is the GM meaning (Chevrolet, Cadillac, GMC). On other makes this number means something else: if your car isn’t made by GM, change the make at the top.
Source: GM 23-NA-102 (static.nhtsa.gov)
The explanation comes from the error code reference in the AvtoElektrik PRO app.