P0186 OBD-II Trouble Code: Fuel Temperature Sensor "B" Circuit Range/Performance

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red stars EXCELLENT RATING ON

Cost of diagnosing the P0186 code

P0186 is a diagnostic trouble code (DTC) for "Fuel Temperature Sensor "B" Circuit Range/Performance". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $154.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $50.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate* Credit towards follow-up repair Earliest Availability
Ford $154.99 $50.0
Toyota $154.99 $50.0
BMW $164.99 $50.0

*Estimates may vary by market

SCHEDULE P0186 DIAGNOSTIC Get a fair and transparent estimate upfront

P0186 trouble code definition

Fuel Temperature Sensor "B" Circuit Range/Performance

What the P0186 code means

P0186 is a generic OBD-II code that is triggered when the fuel temperature sensor B circuit goes out of range during self testing; the sensor voltage falls below or goes above the calibrated limit specifications during the self test.

What causes the P0186 code?

  • The engine control module (ECM) detects the sensor circuit voltage below or above the specified range designed for the sensor when it is tested during startup or during operation.

  • Intermittent wiring or connections

  • ECM or sensor short, or open faults

  • Cold fuel resulting from extreme cold conditions (below -40 degF).

  • A corroded or insecure connector could cause the fuel tank or fuel rail temperature sensor to go out of sensor range .

  • Shorted wiring to the sensor, or internal shorting of a defective ECM

What are the symptoms of the P0186 code?

  • The ECM sets code P0186 to memory and turns on the Check Engine Light.

  • The vehicle will not start if the fuel is frozen from extreme cold or there is water in the fuel.

  • The vehicle will not start or may lose power and stall if the fuel gets too hot and boils off.

  • Excessive additives in the fuel can cause erratic sensor readings and cause the fuel to boil off at lower temperatures causing sensors to malfunction.

How does a mechanic diagnose the P0186 code?

  • Scans codes and documents the freeze frame data, then clears the codes to verify code returns

  • Performs a visual check of all the wiring and connections to the sensor to check for breaks in the wiring or loose connections

  • Disconnects connection to the sensor and checks to see if the sensor is testing within specifications

  • Takes a fuel sample to compare the temperature of the fuel to the sensor input

  • Tests the diesel fuel heater for proper operation to make sure that it is not overheating the fuel

Common mistakes when diagnosing the P0186 code

  • Not doing a visual check of connections to the sensor to make sure they are making good contact to the fuel heater and fuel temperature sensor

  • Not checking the fuel for excessive additives that can cause sensors to malfunction

  • Not retesting the system in a warmer area if the car is in an extremely cold environment (below -40 degrees Fahrenheit) which can cause codes without failure

How serious is the P0186 code?

  • The vehicle will not start if excessive water is in the fuel, the ambient temperature is below freezing, or the fuel heater is defective due to the temperature sensor

  • The engine may misfire, hesitate and stall if the fuel temperature exceeds normal operating temperatures due to the temperature sensor circuit malfunction, or if the fuel rail gets too hot

What repairs can fix the P0186 code?

  • Testing the fuel temperature sensor and replacing it if it goes out of specifications
  • Repairing or replacing a defective connector or wiring to the sensor if it is shorted or open
  • Replacing a defective ECM
  • Replacing the diesel fuel heater and the temperature sensor as an assembly

Additional comments for consideration regarding the P0186 code

The code P0186 may be used on diesel engines with fuel heaters, and on gasoline engines that use two fuel temperature sensors to monitor the fuel temperature in the fuel tank or at the fuel rail. Follow the manufacturer's recommended testing procedures for the vehicle and type of fuel you are working on. Not all temperature sensors are located and tested the same.

Need help with a P0186 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

Check Engine Light
P0186
trouble codes

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0186 code.

SCHEDULE P0186 DIAGNOSTIC
Get a $50 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating

(8600)

Rating Summary
8017
273
65
46
199
8017
273
65
46
199
 at YourMechanic

Brandon

9 years of experience
133 reviews
Brandon
9 years of experience
Ford Escort L4-2.0L - Check Engine Light is on - Nashville, Tennessee
Brandon showed up ahead of schedule, was very personable and diagnosed my problems. He also scheduled my next appointments which will be with him.
 at YourMechanic

William

23 years of experience
33 reviews
William
23 years of experience
Lexus IS250 V6-2.5L - Check Engine Light is on - Mableton, Georgia
Arrived early which was great. William was courteous, and attentive to the issue. Even though it took several attempts I'm so happy he was determined to fix it and he did!
 at YourMechanic

Dan

40 years of experience
1080 reviews
Dan
40 years of experience
Plymouth Grand Voyager - Check Engine Light is on - Lawrenceville, Georgia
Mr. Dan Barber was quite patient, courteous and quite knowledgeable. From my observation, Mr. Barber appears to be quite professional.
 at YourMechanic

Christopher

9 years of experience
120 reviews
Christopher
9 years of experience
Ford Fiesta L4-1.6L - Check Engine Light is on - Smyrna, Georgia
Chris communicated with us each step of the way up until his arrival. He listened well, was knowledgeable, and was prepared. He took the time to diagnose the problem, explained the what, why and how and provided a solution. I would definitely recommend him and will use him again.


More related articles

P2127 OBD-II Trouble Code: Throttle/Pedal Position Sensor/Switch 'E' Circuit Low
P2127 code definition The P2127 code is a generic OBD-II diagnostic trouble code indicating a fault with the throttle or pedal position...
P2562 OBD-II Trouble Code: Turbocharger Boost Control Position Sensor Circuit
P2562 Code Definition The P2562 code is a generic powertrain code related to vehicle speed control and the idle control system. It...
P2723 OBD-II Trouble Code: Clutch Pressure Control Solenoid 5 - Stuck Off
P2723 means a solenoid has malfunctioned due to low fluid levels, a failing transmission, faulty sensor or solenoid, or electrical issues or problems.

Related questions

Key won't turn, Check Engine light on.
If it is the correct key and it is inserted all of the way in, then most likely the cylinder is bad. Wiggle the key around while trying to turn it. It may eventually unlock and turn, but this problem...
Check engine light on
Hi there. Since the Check Engine Light is on then the computer needs to be scanned for codes (https://www.yourmechanic.com/article/how-to-read-and-understand-check-engine-light-codes-by-jason-unrau) first. I usually do this before going any further with it. This can be caused by any number of sensors on...
Engine losing power, gas pedal unresonsive
Hello there, a few common faults can cause these type of symptoms. The most common would be the vehicle going into limp mode, a fuel pump (https://www.yourmechanic.com/services/fuel-pump-replacement) problem, bad spark plugs (https://www.yourmechanic.com/services/spark-plugs-replacement), faulty MAF sensor (https://www.yourmechanic.com/services/mass-airflow-sensor-replacement), a vacuum leak, or...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com