P0189 Fuel Temperature Sensor B Circuit Intermittent

P0189 indicates an intermittent fuel temperature sensor B circuit fault. The second fuel temperature signal jumps, drops out, or becomes unstable.

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 clear intermittent sensor B faults without stressing the connector and reproducing the unstable signal.

Symptoms of P0189

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 P0189

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

Graph fuel temperature B during road vibration, hot soak, fuel pump operation, and harness movement around the sensor.
Inspect terminal tension, connector locking, corrosion, fuel contamination, shared reference stability, and harness rub points.
Compare intermittent temperature movement with fuel pressure, fuel composition, trim behavior, and freeze-frame conditions.

Related OBD-II codes

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