The controller detected an electrical or performance fault in the bank 1 sensor 1 heater circuit.
Why this matters
A trouble code reports a monitored result. It narrows the system and test conditions, but it rarely names the failed part by itself.
Evidence to capture first
- Battery voltage and heater command at code-set conditions
- Heater supply, control, resistance, and current using the correct pinout
- Connector heat damage, water entry, harness routing, and shared fuse loads
A disciplined path
- Identify the exact sensor location from service data
- Test power and control without spreading terminals
- Compare current rise and control response with specifications
- Repair wiring or replace the sensor only when the failed element is isolated
Decision point
The repair is supported when the failed circuit, mechanical condition, or monitored response is measured and the original monitor can run without the fault returning.
Source desk
Use current model-specific service information for specifications, connector locations, disabling procedures, and tightening values. The following public resources support the broader safety or system context used in this guide.
KEEP EXPLORING
Related guides
P0171 System Too Lean Bank 1: A Fuel-Trim Workflow
The controller reached a calibrated positive fuel correction because feedback indicated a lean condition on bank 1.
Read guideP0128 Coolant Temperature Below Thermostat Regulating Range
Warm-up behavior did not match the calibrated time and load model, commonly because measured coolant temperature rises too slowly.
Read guide
C0035 Left-Front Wheel-Speed Circuit: Signal Before Sensor
A chassis controller detected a left-front wheel-speed circuit or signal fault; code wording varies by manufacturer.
Read guide