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P0186 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


The P0186 DTC code relates to a problem related to the ‘B’ circuit range and performance of the fuel temperature sensor. The OBD II system is designed to monitor a number of components related to the fuel system, emissions, and engine performance using this code.


When the OBD-II system detects that the fuel temperature sensor ‘B’ circuit is operating outside of the expected range or exhibiting performance issues, it triggers the P0186 code. The fuel temperature sensor is responsible for measuring the temperature of the fuel in the tank and providing important data to the vehicle’s engine control module (ECM).


The P0186 error code has a number of possible sources that it may arise from:

  • A fuel temperature sensor that is faulty: If the sensor isn’t working properly, it won’t be able to provide correct readings or any data at all.
  • Wiring Problems: Corroded or damaged connections and wiring for the fuel temperature sensor might cause signal disruption.
  • Fuel Temperature Sensor Circuit: Short circuits or open circuits inside the circuit may result in a code.
  • ECM Malfunction: The engine control module may malfunction under specific circumstances, misinterpreting sensor data and activating the code.


The P0186 DTC may cause the following performance issues in the car:

  • Check Engine Light: The primary symptom is the illumination of the Check Engine 
  • Light on the dashboard. a. Reduced Fuel economy: Because the ECM uses fuel temperature information to optimize fuel supply, a malfunctioning sensor might reduce fuel economy.
  • Harsh Idling: On occasion, the engine may have trouble starting or engage in harsh idling.


An experienced mechanic or expert will carry out the following procedures to troubleshoot the P0186 code:

  • OBD-II Scanner: The first step is to use an OBD-II scanner to retrieve the trouble code and any related codes stored in the system.
  • Visual Inspection: To look for any evident problems, the sensor, wiring, and connections will be visually inspected.
  • Testing the Fuel Temperature Sensor: A multimeter will be used to test the sensor’s resistance and voltage to see if it is operating properly.
  • Examining the wire: The technician will look for corrosion or damage in the wire and connections.
  • ECM Testing: If all other parts are in working order, it could be necessary to test or reprogram the ECM.

Common mistakes

Some frequent errors to avoid throughout the diagnostic and repair procedures include:

  • Ignoring Wiring Inspection: By skipping a comprehensive inspection of the wiring and connectors, the problem’s underlying causes may go unnoticed.
  • Replacing Components Unnecessarily: To precisely identify the damaged part and prevent needless replacements, it’s crucial to use a methodical technique.

How serious is this?

Driving conditions and the severity of symptoms shall be taken into account in determining the seriousness of the P0186 code. While the vehicle may still be operable, ignoring the issue could lead to decreased fuel efficiency and potential engine performance problems.

What repairs can fix the code?

repair manuals

Following diagnosis, the following fixes could be required to fix the P0186 code:

  • Replacing the Fuel Temperature Sensor: A new sensor must be installed if the old one is malfunctioning.
  • Wiring and Connector Repair or Replacement: Damaged parts will need to be repaired or replaced.
  • ECM Reprogramming or Replacement: The ECM could occasionally need to be reprogrammed or replaced.

Related codes

Other related codes that may accompany P0186 include P0185 (Fuel Temperature Sensor ‘B’ Circuit), P0187 (Fuel Temperature Sensor ‘B’ Circuit Low Input), and P0188 (Fuel Temperature Sensor ‘B’ Circuit High Input).


For the vehicle owner, P0186 DTC codes may be a problem, but they can be resolved with an appropriate diagnosis and timely repair. In order to avoid more serious issues in the future, it may be helpful to maintain and correct all checking engine lights as soon as possible. If your vehicle encounters the code P0186, you should not hesitate to contact a qualified automotive professional for assistance in regaining optimum performance.

P0186 Code – What Does It Mean & How To Fix It