P0186 — Fuel Temperature Sensor B Circuit Malfunction
Drive with caution — fix soon.
What P0186 means
This code means the computer has detected a general malfunction in the fuel temperature sensor 'B' circuit, a second sensor used on some vehicles to monitor fuel temperature. The cause is usually a failed sensor, damaged wiring, or a poor connector, just like the 'A' circuit codes. Common fixes include repairing the wiring or connector, or replacing the affected fuel temperature sensor.
Common symptoms
- Check engine light is on
- Slightly reduced fuel economy
- Minor rough idle or hesitation
- Possible hard starting in extreme temperatures
- Often no noticeable driving symptoms
Common causes
- Failed fuel temperature sensor B
- Open or shorted sensor wiring
- Corroded or loose sensor connector
- Damaged wiring harness near the fuel system
- Faulty engine control module (rare)
Typical repair cost
$110 – $360
Varies by vehicle and root cause.
Frequently asked questions
Can I keep driving with a P0186 code?
Yes, in most cases you can drive normally since this fault rarely affects everyday performance. Still, it's wise to have it diagnosed within a week or two so a minor sensor or wiring issue doesn't get worse.
How much does it cost to fix a P0186 code?
Most repairs fall between $110 and $360. A wiring or connector repair is cheaper, while replacing the 'B' fuel temperature sensor adds parts and labor depending on the vehicle.
Is a P0186 code serious?
It's a moderate-severity code. It generally won't leave you stranded, but since the sensor helps the engine run efficiently, fixing it keeps your fuel economy and emissions in good shape.
What's the difference between P0186 and P0181?
Both are fuel temperature sensor circuit malfunctions, but P0181 refers to sensor 'A' and P0186 refers to a second sensor, 'B'. Some vehicles use two fuel temperature sensors, and this code points specifically to the second circuit.