What does it mean?
P1541 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: HTRS Passenger Heater Standby Circuit Low Input .
Symptoms
- Check engine light on together with heater related codes
- Auxiliary heater does not run at all, or shuts down soon after starting
- Cabin takes much longer to warm up in cold weather
- Pre-heating cannot be started from the timer or the remote control
- Heater status indicator behaves oddly or stays off
- Engine performance and fuel consumption are otherwise normal
Likely causes
- Standby signal wire shorted to ground where the harness is chafed or trapped
- Water ingress into the heater unit connector, which usually sits in an exposed area
- Blown fuse or missing supply to the auxiliary heater, so it can never report ready
- Poor or corroded ground point for the heater unit
- Internal fault in the auxiliary heater control unit
- Harness damage where it passes into the engine bay or a wheel arch
- Receiving module input circuit failure
How to fix it
- Read all stored codes, including those from the heater unit, to see how far the fault spreads
- Check the fuses and supply voltage feeding the auxiliary heater
- Inspect the heater connector for water, corrosion and damaged terminals
- Measure the standby circuit voltage with the heater unplugged; a low reading with the connector open indicates a wiring short
- Check the wire along its whole route for a short to ground and repair the damaged section
- Test the heater ground with a voltage drop measurement
- Activate the heater with a scan tool, and replace the heater control unit only after the wiring is proven good