P0185: Fuel temperature sensor B circuit malfunction — what it means, the affected system and what to check before replacing parts.
Meaning, symptoms, causes and checks
The definition identifies an electrical malfunction in the fuel temperature sensor B circuit. It identifies the monitored circuit but does not determine whether the sensing element, actuator, connector, wiring, supply, ground or control-module input is responsible; the circuit layout and diagnostic thresholds depend on the exact vehicle.
Affected system: Fuel-temperature sensing
Symptoms
- Illuminated Check Engine light
- Decreased fuel economy
- Hard starting in cold weather
- Engine stalling or hesitation
- Rough engine idling
Possible causes
- Faulty fuel temperature sensor B
- Damaged or chafed sensor wiring
- Corroded or loose electrical connector
- Short circuit to ground or power in the harness
- Internal ECU signal processing failure
What to check
- Inspect the sensor connector for corrosion or loose pins
- Measure the resistance of the sensor using a multimeter
- Check the wiring harness for continuity and short circuits
- Verify the reference voltage supplied by the engine control module
- Monitor live data parameters to check for erratic temperature readings
Also written as: P0185-00, P018500, PO185 (some scan tools add the fault-type byte, e.g. -00).