P0188Fuel Temperature Sensor B Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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. P0188 means the signal of sensor B is above its valid range – typically an open circuit or unplugged connector, so the module would read about −40 to −50 °C. GM's 6.6 litre diesel sets it above 4.75 V (below about −50 °C) for 5 s; on GM's direct-injection petrol engines the digital rail temperature sensor 2 sets it above a count of 1865, after two trips.
- What you may notice
- Check engine light on
- Fuel temperature about −40/−50 °C in scan data
- Usually no change in driving
- Likely causes
- LikelyConnector off or wire open
- LikelySensor open internally
- PossibleSensor ground open or short to 5 V
- RareEngine control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €50 – €400
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.