P0187 code meaning
Fuel Temperature Sensor B Circuit Low
Powertrain system Generic code P01xx codes Check engine light
What P0187 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. P0187 means the signal of sensor B is below its valid range – with an analogue NTC a short to ground or very hot reading. GM's 6.6 litre diesel sets it below 0.60 V (above about 150 °C) for 5 s; GM's direct-injection gasoline engines use a digital rail temperature sensor 2 and set it below a count of 145 in 50 of 62 samples, two trips – communication faults of these digital sensors have codes of their own.
P0187 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 P0187
- Check engine light on
- Implausibly high fuel temperature in scan data
- Possibly starting problems
Common causes of P0187
- Most likelySignal wire shorted to ground (chafing)
- Most likelySensor shorted internally
- PossibleMoisture or corrosion in the connector
- 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 P0187 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. |
| 87 | The exact fault in that area. |
What to do next
- Note P0187 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 P0187
What does P0187 mean?
P0187 means "Fuel Temperature Sensor B Circuit Low". 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 P0187?
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 P0187 fail an emissions test?
Yes, it can. P0187 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 P0187 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will P0187 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.