P0186
Fuel Temperature Sensor B Circuit Range/Performance
Fuel temperature sensor
Generic OBD-II
Low
What it means
P0186 means the fuel temperature sensor "B" is giving a reading that's out of its normal range or doesn't respond as expected. The ECM uses fuel temperature to fine-tune injection and compensate for fuel density. A skewed reading can slightly affect fuel economy and driveability, but on its own it rarely changes how the car runs.
Low
Can I keep driving? Yes — this sensor mainly fine-tunes fueling; the car drives normally, though fuel economy and cold or hot-fuel behaviour may be slightly off until it's fixed.
Common symptoms
What you'll notice
- Check-engine light on
- Reduced fuel economy
- Slightly rough idle or minor hesitation
- Fuel temperature reading on a scan tool that looks implausible
Common causes
Most likely first
- Faulty or lazy fuel temperature sensor BLikely
- Corroded or loose sensor connectorCommon
- Damaged wiring in the sensor circuitCommon
- Rarely, an ECM faultLess often
How to diagnose & fix
Work through it in order
- Read live data and compare the fuel temperature reading to ambient and coolant temps after a cold soak.
- Inspect the sensor connector and wiring for corrosion or damage.
- Measure the sensor's resistance against spec across temperature.
- Replace the fuel temperature sensor B if it reads out of range.
- Clear the code and re-test.
FAQ
Quick answers
Is it safe to drive with P0186?+
Yes. This is a low-impact sensor fault that won't strand you. Fixing it keeps fueling accurate, but it isn't urgent.
Can I just clear P0186?+
It may clear briefly, but if the sensor or wiring is faulty the code returns after the ECM re-checks the reading.
Related codes
Often seen with P0186
Read & clear P0186 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX