Powertrain, generic · Fuel and air metering

P0189 Fuel Temperature Sensor B Circuit Intermittent

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

Fuel temperature sensor B is an NTC thermistor: the hotter the fuel, the lower its resistance and signal voltage. On diesels it sits in the injection pump, rail or return line; on Ford petrol direct-injection engines it is built into the rail pressure sensor, and GM uses digital rail temperature sensors on its direct-injection engines. Sensor B is the second measuring point, for example GM's 6.6 litre diesel sensor 2 or a second rail. P0189 covers jumps or brief dropouts of sensor B, the counterpart of P0184. GM documents a gradient check for sensor A (new value outside a filtered window, 10 of 15 samples); no manufacturer using P0189 was found, so the description rests on CARB and that sensor A strategy. Loose contacts and wire breaks from vibration are the typical causes.

Likely causes

Loose contact or weak terminal tension in the connector
Wire break or chafing from vibration
Sensor with internal dropouts

Symptoms

  • Check engine light on
  • Jumping readings

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€30–350
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

fuel temperature sensor bsensor wiring

Related codes

P0185P0186P0187P0188P0184

References: law.cornell.edu, gsi.ext.gm.com.