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 torque sensor on the steering shaft or its connector
- The power steering ECU connector: corrosion, poor contact
- A wire next to the steering rack has chafed on its mount (per a GM bulletin — the A/C compressor wire)
- The power steering ECU
What you can do yourself
- The power steering may switch off — the steering will get very heavy, especially at low speed. If this happens while driving, hold the wheel with both hands, slow down and stop in a safe place.
- Check the battery, terminals, ground and the power steering fuse: at low voltage the assist weakens or switches off.
- If the code has the suffix 4B, the sensor isn’t calibrated (after a rack or unit replacement): the calibration is done with a scanner.
- Inspect the wires by the steering rack: are they rubbing on the rack mount, is any insulation worn through.
- Don’t clear the codes before diagnosis: they tell the technician what happened.
Stop and don’t drive on if:
- The red brake light is on, or the brake pedal feels soft or sinks
- The steering became very heavy, or the car pulls to one side when braking
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 PIT5213B, PIT5508 (static.nhtsa.gov)
The explanation comes from the error code reference in the AvtoElektrik PRO app.