What Does P0186 Mean?
The fuel temperature sensor B circuit is reporting values outside the expected range for current operating conditions. The ECM has determined the sensor reading does not correlate logically with engine temperature, ambient temperature, or operating time. The driver may notice no obvious driveability symptoms, or possibly slight changes in fuel economy.
Common Causes
35%
Faulty fuel temperature sensor B providing inaccurate but in-range readings
25%
High resistance in the sensor circuit wiring causing voltage offset
20%
Contaminated or fuel-soaked sensor causing reading drift
12%
Incorrect sensor installed (wrong resistance curve for application)
8%
ECM calibration or reference voltage issue
Diagnostic Steps
1
Compare the fuel temperature sensor B PID reading against fuel temperature sensor A (if equipped) and engine coolant temperature after a cold soak — all should read within a few degrees of ambient temperature.
2
Measure the sensor resistance with a multimeter and compare to the manufacturer's resistance-vs-temperature chart. A typical NTC sensor reads ~2.4 kΩ at 68°F.
3
Verify the 5V reference voltage at the sensor connector with the sensor unplugged — it should read 4.9–5.1V. Low reference voltage indicates a shared circuit issue.
4
Check for fuel contamination or debris around the sensor tip that could insulate it from the fuel and cause inaccurate readings.
5
Inspect the sensor connector and wiring for corrosion or high-resistance connections. Measure voltage drop across each connection while the circuit is active.
Estimated Repair Cost
$50 - $250
Parts + labor, varies by vehicle and location
The fuel temperature sensor B circuit is reporting values outside the expected range for current operating conditions. The ECM has determined the sensor reading does not correlate logically with engine temperature, ambient temperature, or operating time. The driver may notice no obvious driveability...
The most common cause of P0186 (Fuel Temperature Sensor B Circuit Range/Performance) is: Faulty fuel temperature sensor B providing inaccurate but in-range readings
Typical repair costs for P0186 range from $50 to $250, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. The ECM will compensate with default fuel temperature values. Fuel economy may be slightly reduced, but there is no safety risk. Repair at your convenience.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0186 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Generic (SAE)
Recommended Tools
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