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P0185 is a diagnostic trouble code (DTC) for "Fuel Temperature Sensor "B" Circuit Malfunction". 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 $70.00. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $30.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
Fuel Temperature Sensor “B” Circuit Malfunction
The engine control module (ECM) sees that the sensor circuit is malfunctioning below or above the specified range designed for the sensor.
The code could be set if the fuel is too hot or too cold.
The fuel tank or fuel rail temperature sensor is out of sensor range or the connector is corroded.
The ECM monitors the temperature of the diesel fuel when the fuel heater is activated. If the temperature is out of range, it will turn on the Check Engine Light and set the code.
The vehicle will not start if the fuel is frozen from extreme cold conditions and water in the fuel.
If the fuel is too hot and is boiling, then the vehicle will not start, may stall, or loose power.
Excessive additives in the fuel can cause erratic sensor readings and cause the fuel to boil off at lower temperatures which would cause the sensor to malfunction.
The ECM sets code P0185 and turns on the Check Engine Light.
Scans codes and documents the freeze frame data then clears the codes to verify if it 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 temperature of fuel to the sensor input
Tests the diesel fuel heater for proper operation to make sure it is working to heat the fuel without overheating the fuel
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.
The vehicle will not start If it has excessive amounts of water in the fuel, below freezing ambient temperature, and a defective fuel heater due to the temperature sensor.
The engine may misfire, hesitate, and stall if the fuel temperature exceeds normal operating temperature. This is a result of the temperature sensor circuit malfunctioning or the fuel rail getting too hot.
Testing the fuel temperature sensor and replacing it if it is out of specifications
Repairing or replacing a defective connector or wiring to the sensor
Replacing the diesel fuel heater assembly with the temperature sensor
The code P0185 is used on vehicles that have two fuel temperature sensors. Code P0180 is for sensor A and P0185 is for sensor B. Follow the manufacturer's recommended testing procedures for the vehicle and type of fuel you are working on.
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.