P0186
Fix within 1-2 weeksYour engine computer detects inconsistent or erratic signals from the Fuel Temperature Sensor 'B' circuit.
Code P0186 means your fuel temperature sensor B is sending inconsistent readings. Common causes: Faulty sensor (65%), wiring issues (30%). Drivability: Yes, safe to drive, but fix soon. Repair cost: $50-$200 DIY, $150-$500 professional.
Can I Drive With P0186?
Yes, safe to drive
No restrictions, but fix within 1-2 weeks to prevent further issues.
Stop driving immediately if: Flashing Check Engine Light, significant power loss, or strong fuel smell.
Symptoms of P0186
- 1Check Engine Light is on
- 2Engine is hard to start, especially when cold or hot
- 3Poor fuel economy
- 4Engine runs rough or idles poorly
- 5Reduced engine power
Common Causes of P0186
Parts most likely causing this code, ranked by probability
The sensor itself is failing intermittently, sending incorrect or fluctuating fuel temperature data to the engine computer.
65% of P0186 cases are fixed by replacing this sensor
Damaged, corroded, or loose wiring or a faulty connector prevents a consistent signal from reaching the engine computer.
30% of P0186 cases are fixed by repairing wiring or connectors
A rare internal fault within the engine computer's sensor input circuit can cause it to misinterpret the fuel temperature signal.
5% of P0186 cases are fixed by replacing the PCM
Check These First (Before Buying Parts)
- Visually inspect the wiring harness and connector for the Fuel Temperature Sensor 'B' for any obvious signs of damage, fraying, or corrosion.
- Ensure your gas cap is securely tightened, as a loose cap can sometimes trigger fuel system-related codes (though less common for P0186).
How to Diagnose P0186
- 1Connect an OBD-II scan tool to confirm the P0186 code and check for any other related codes.
- 2Inspect the wiring harness and connector leading to the Fuel Temperature Sensor 'B' for any visible damage, corrosion, or loose connections.
- 3Using a multimeter, test the resistance of the Fuel Temperature Sensor 'B' at various fuel temperatures (if accessible) to check for erratic readings.
- 4Monitor live data from the Fuel Temperature Sensor 'B' using a scan tool to observe its readings for intermittency or sudden drops/spikes.
- 5If the sensor is integrated into the fuel pump assembly, consider testing the entire assembly if the sensor itself cannot be isolated.
P0186 on Popular Vehicles
Ford F-150
2004-2024The fuel temperature sensor 'B' is often part of the fuel pump assembly on these trucks. This makes the repair more complex as the fuel tank must be dropped to access it.
70% fixed by replacing the fuel pump assembly
Chevrolet Silverado
2007-2024Similar to Ford, the fuel temperature sensor 'B' on many Silverado models is integrated into the fuel pump module, requiring tank removal for replacement.
65% fixed by replacing the fuel pump assembly
Honda Accord
2003-2024On some Accord models, the fuel temperature sensor 'B' might be a separate component or part of the fuel sender unit, which is typically more accessible than a full fuel pump replacement.
75% fixed by replacing the sensor or repairing wiring
Frequently Asked Questions
What does P0186 mean?
P0186 indicates that your vehicle's engine computer is receiving intermittent or erratic signals from the Fuel Temperature Sensor 'B' circuit, which is used to measure the temperature of the fuel.
Can I drive with P0186?
Yes, you can drive safely with P0186, but you should fix it within 1-2 weeks. The engine computer will use a default value for fuel temperature, which can lead to poor fuel economy, rough idling, or hard starting. It will not cause immediate breakdown.
Will P0186 clear itself?
No, P0186 will not clear itself. The engine computer stores this code because it detects a persistent issue with the fuel temperature sensor 'B' circuit. You must diagnose and repair the underlying problem, then clear the code with an OBD-II scan tool.
How do I fix P0186 myself?
Start by inspecting the wiring and connector to the fuel temperature sensor 'B' for damage. If they look good, test the sensor with a multimeter. If the sensor is faulty, replace it. If the sensor is integrated into the fuel pump assembly, you might need to replace the entire assembly.
How much does it cost to fix P0186?
DIY repair costs for P0186 range from $50 to $200, primarily for a new fuel temperature sensor or wiring repair. Professional shop costs typically range from $150 to $500, depending on labor rates and whether the sensor is separate or part of the fuel pump assembly.
P0186 keeps coming back - why?
If P0186 keeps returning, it means the root cause was not fully addressed. This often happens if you only replaced the sensor but had a wiring issue, or if the sensor is integrated into a larger assembly (like the fuel pump) that also has a problem. A faulty PCM is a rare but possible cause for recurrence.
Will P0186 fail emissions/smog test?
Yes, P0186 will cause your vehicle to fail an emissions or smog test. The Check Engine Light being on is an automatic failure in most jurisdictions, and an erratic fuel temperature reading can directly impact fuel mixture and exhaust emissions.
What's the difference between P0186 and P0185?
P0185 indicates a general 'malfunction' in the Fuel Temperature Sensor 'B' circuit, meaning the computer sees a problem but not necessarily an intermittent one. P0186 specifically points to an 'intermittent/erratic' signal, suggesting the sensor or its connection is failing inconsistently rather than being completely open or shorted.
P0186 on Ford F-150
On many Ford F-150 models, the Fuel Temperature Sensor 'B' is integrated into the fuel pump module located inside the fuel tank. This means replacing the sensor often requires replacing the entire fuel pump assembly, which is a more involved repair.
Questions to Ask Your Mechanic
Did you check the live data from the Fuel Temperature Sensor 'B' for erratic readings?
Good answer: Yes, I monitored the sensor's voltage and temperature readings on the scan tool. They were fluctuating wildly, confirming an intermittent signal.
What did you find when inspecting the wiring and connector to the sensor?
Good answer: I found some corrosion in the connector pins, which I cleaned, or a frayed wire that I repaired. The circuit now shows good continuity.
Repair Cost Estimate
DIY Repair
Parts only
$50-$200
Shop Repair
Parts + labor
$150-$500
Save $100-$300 by doing it yourself
Difficulty
intermediate
Time
1-3 hours
Intermediate - Requires basic diagnostic tools like a multimeter and scan tool, and potentially specialized tools for fuel line disconnection or fuel tank removal if the sensor is integrated into the fuel pump.
Cost of Waiting
Ignoring P0186 can lead to consistently incorrect fuel mixture calculations. This results in reduced fuel economy, increased emissions, and over time, can cause premature wear on engine components or damage your catalytic converter ($800-$2,500 repair). A $50 sensor fix now prevents a much larger bill later.
While You're In There...
If the fuel temperature sensor 'B' is integrated into the fuel pump assembly and you are replacing the entire unit, it makes sense to replace the fuel filter (if accessible and not a lifetime filter) to ensure clean fuel delivery.
If the fuel temperature sensor 'B' is integrated into the fuel pump assembly and the sensor is confirmed faulty, replacing the entire assembly is often the only way to fix the sensor, and it refreshes a critical component.
Tools You'll Need
- OBD-II Scan Tool
- Multimeter
- Basic hand tools (sockets, wrenches)
- Wire strippers/crimpers (if wiring repair needed)
- Fuel line disconnect tools (if sensor is in fuel tank)
- Fuel tank jack (if fuel pump assembly needs replacement)
P0186 is a common sensor code. Most repairs involve replacing a relatively inexpensive sensor or fixing a simple wiring issue, and your vehicle's fuel system will operate correctly afterward.
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Your Next Steps
Step 1: Inspect the wiring and connector to the Fuel Temperature Sensor 'B'. Look for any visible damage, corrosion, or loose pins. Clean any corrosion and secure connections.
Step 2: If the wiring and connector are good, use an OBD-II scan tool to monitor the live data from the Fuel Temperature Sensor 'B'. If the readings are erratic or stuck, the sensor is faulty.
Step 3: If the sensor is faulty, replace the Fuel Temperature Sensor 'B'. Be aware that on many vehicles, this sensor is integrated into the fuel pump assembly, requiring replacement of the entire unit.