P0185 Fuel Temperature Sensor B Circuit Malfunction

P0185 indicates a fuel temperature sensor B circuit malfunction. The controller cannot trust the second fuel temperature input.

Code details

Generic OBD-II · P0

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not replace fuel delivery parts until fuel temperature sensor B circuit integrity is confirmed.

Symptoms of P0185

Check-engine light on, sometimes with rough or uneven running.
Hesitation, surging, or a noticeable change in fuel economy.
Occasionally hard starting or a smell of unburnt fuel.

Common causes of P0185

A failing or contaminated sensor (MAF, MAP, oxygen or air-fuel sensor).
Intake or vacuum leaks, or an exhaust leak near an upstream sensor.
Wiring, connector, or fuel-delivery problems that skew the reading.

Useful checks before replacing parts

Compare fuel temperature sensor B with sensor A, ambient, coolant, intake temperature, and expected fuel-system temperature.
Check sensor signal voltage, reference, ground, connector condition, harness continuity, and contamination at fuel connectors.
Review whether sensor B data affects pressure control, fuel composition, cold start, or related fuel trim faults.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.