P0188 code meaning
Fuel Temperature Sensor B Circuit High
Powertrain system Generic code P01xx codes Check engine light
What P0188 means
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 gasoline 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 gasoline engines the digital rail temperature sensor 2 sets it above a count of 1865, after two trips.
P0188 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairAfter a drive cycle
Symptoms of P0188
- Check engine light on
- Fuel temperature about −40/−50 °C in scan data
- Usually no change in driving
Common causes of P0188
- Most likelyConnector off or wire open
- Most likelySensor open internally
- PossibleSensor ground open or short to 5 V
- Less likelyEngine control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel temperature sensor bSensor wiring
What each part of P0188 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 1 | Area: fuel and air metering. |
| 88 | The exact fault in that area. |
What to do next
- Note P0188 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0188
What does P0188 mean?
P0188 means "Fuel Temperature Sensor B Circuit High". Fuel temperature sensor B is an NTC thermistor: the hotter the fuel, the lower its resistance and signal voltage. It is a generic code, so it means the same on every make.
Is it safe to drive with P0188?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P0188 fail an emissions test?
Yes, it can. P0188 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P0188 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will P0188 clear itself after the repair?
After the repair the car has to complete a drive cycle (a mix of city and highway driving) before the test runs again. Until then the readiness monitor shows "not ready", which can fail an inspection.