What does it mean?
P1521 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Power Steering Switch Input Circuit Malfunction .
Symptoms
- Check engine light on with normal driving otherwise
- Idle drops or the engine stalls when the wheel is turned at parking speed
- No idle-up compensation during tight manoeuvres
- Rough idle when the steering is held on full lock
- Occasional stall when parking with the A/C running
- Steering effort itself may feel normal
Likely causes
- Failed power steering pressure switch stuck open or closed
- Fluid leak at the switch contaminating its connector
- Chafed or broken wire between the switch and the module
- Corroded connector terminals in a location exposed to road spray
- Low power steering fluid or a restricted line, so pressure never reaches the switch threshold
- Worn steering pump producing pressure outside the expected range
- Module input circuit failure as the last possibility
How to fix it
- Monitor the power steering switch input in live data while turning the wheel from lock to lock
- Check the fluid level and inspect the switch area for leaks and contamination
- Unplug the switch and bridge the connector briefly to see whether the module input state changes, which separates wiring from switch
- Measure the switch continuity in both states with a pressure load applied
- Check the wire for continuity to the module and for a short to ground
- Replace the power steering pressure switch if it does not change state
- Repair the harness or connector, then confirm the idle-up works during a parking manoeuvre