P0186 Fuel Temperature Sensor B Circuit Range/Performance

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. P0186 is the plausibility check of sensor B, the counterpart of P0181 – presumably a comparison with a reference sensor after a long standstill, as GM documents for sensor A (8 h, 20 °C). No manufacturer using P0186 was found; the description rests on CARB and the sensor A strategy.

Likely causes

Symptoms

• Check engine light on
• Usually no change in driving

Repair estimate

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

Parts involved

Related codes

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