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

Our certified mechanics come to you · 12-month, 12,000-mile warranty

SCHEDULE P0186 DIAGNOSTIC 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. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 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$20.00
Toyota$20.00
BMW$20.00
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 1-800-701-6220.

trouble codes
P0186
Check Engine Light

Fast and easy Check Engine Light is on Inspection service at your home or office.

SCHEDULE P0186 DIAGNOSTIC
Get a fair and transparent estimate upfront

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.8/5

Number of Reviews

4,810

Rating Summary
4,424
187
47
28
124
4,424
187
47
28
124

Joel

19 years of experience
741 reviews
Joel
19 years of experience
Acura RL - Check Engine Light is on - Jacksonville, Florida
very knowledgeable and precise. able to fix electrical issues in my car. Right on time for the appointment.

Christopher

15 years of experience
41 reviews
Christopher
15 years of experience
Honda Accord - Check Engine Light is on - Fairburn, Georgia
Christopher was excellent! He explained everything in detail to make sure I understood. He was professional and provided me with the next course of actions to resolve my care issues. I'm glad he was sent to service my car.

Alexander

18 years of experience
58 reviews
Alexander
18 years of experience
Saab 9-7x - Check Engine Light is on - Kissimmee, Florida
He was very friendly and very helpful . I felt like it was being around a close friend , also gave me so very good advice on my car & future advice about it . Highly recommend mechanic, would use his services again .

Matthew

31 years of experience
639 reviews
Matthew
31 years of experience
Jeep Patriot - Check Engine Light is on - Norfolk, Virginia
Matthew was on time which was a relief, he is very knowledgeable and was easy to understand what was wrong and what was being done. I am recommending to friends and family due to the great experience Matthew gave me. Extremely professional 10/10

More related articles

P0095 OBD-II Trouble Code: Intake Air Temperature Sensor 2 Circuit
P0095 P0095 code definition Intake Air Temperature Sensor 2 Circuit What the P0095 code means The intake air temperature sensor transmits a signal correlating to the density of the air coming through the intake to the Engine Control Module (ECM)....
P0293 OBD-II Trouble Code: Cylinder 11 Contribution/Balance Fault
P0293 P0293 Code Definition Cylinder 11 Contribution/Balance Fault What the P0293 code means The P0293 code indicates that the number eleven cylinder in your vehicle’s firing order is undergoing a fuel-related problem. Please note that P0293 is a generic code,...
P2619 OBD-II Trouble Code: Crank Position Signal Output Circuit Open
P2619 means an issue with the crankshaft position sensor which may cause rough idling and acceleration, engine misfires and poor engine performance.

Related questions

Check Engine Light is on and Autozone read: Trouble Code P0138 O2 Sensor Bank 1 Sensor 2 High Voltage

Hello. If it has a code for an oxygen sensor then that may be the issue. The thing about the oxygen sensors though is that they can give a false reading if there is something else going on with the...

Slow/no acceleration high RPMs

Hey there. When the transmission control module detects a problem (i.e. faulty sensors, low fluid, etc.) the Check Engine Light will come on, and it will go into a "limp" mode. This limp mode will cause the car to drive...

I get a check-engine light and Reduced power. Throttle not responding on hill climbs.

Hi there. The first thing to do is get a code reader and check the codes that the engine has stored since the engine light is on. This will give you a starting point and a place to check for...

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.

1-800-701-6230 · hi@yourmechanic.com