P0187: Fuel Temperature Sensor B Circuit Low Input

Definition

The OBD2 code P0187 indicates that the fuel temperature sensor B is providing a low voltage input signal, which may suggest a malfunction in the sensor or its circuit

Common causes

Faulty fuel temperature sensor
Damaged wiring or connectors
Short circuit in the sensor circuit
Open circuit in the sensor circuit
Poor ground connection
Faulty engine control module (ECM)

Common misdiagnoses

Faulty fuel temperature sensor
Wiring issues or short circuits
Fuel pump problems
Engine control module (ECM) issues
Fuel pressure regulator malfunction
Injector problems
Fuel system leaks
Other sensor failures (e.g., coolant temperature sensor)

Troubleshooting steps

1. Check for Additional Codes

Use an OBD-II scanner to check for any other trouble codes that may be present. This can help identify if there are related issues
2. Inspect Wiring and Connectors
3. Visually inspect the wiring and connectors associated with the fuel temperature sensor B. Look for signs of damage, corrosion, or loose connections
4. Ensure that the wiring is not pinched, frayed, or exposed to heat sources
5. Test the Fuel Temperature Sensor
6. Use a multimeter to test the resistance of the fuel temperature sensor. Compare the readings to the specifications provided in the vehicle's service manual
7. If the sensor is out of specification, it may need to be replaced
8. Check the Sensor Circuit
9. With the multimeter, check the voltage at the sensor connector with the ignition on (engine off). You should see a reference voltage (usually around 5V)
10. If the voltage is low or absent, trace the circuit back to the engine control module (ECM) to identify any breaks or shorts
11. Inspect the ECM
12. If the sensor and wiring are in good condition, the issue may lie with the ECM itself. Check for any software updates or known issues with the ECM for your vehicle model
13. In some cases, reprogramming or replacing the ECM may be necessary
14. Check for Fuel System Issues
15. Ensure that the fuel system is functioning properly. Low fuel pressure or other fuel delivery issues can sometimes trigger sensor codes
16. Inspect the fuel pump, fuel filter, and fuel lines for any blockages or malfunctions
17. Clear the Codes and Test Drive
18. After performing repairs or replacements, clear the trouble codes using the OBD-II scanner
19. Take the vehicle for a test drive to see if the code returns. Monitor the fuel temperature readings if your scanner allows it
20. Consult a Professional
21. If you are unable to resolve the issue after these steps, it may be best to consult a professional mechanic who has experience with your specific vehicle make and model. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P0187 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Additional Codes

2. Inspect Wiring and Connectors

3. Visually inspect the wiring and connectors associated with the fuel temperature sensor B. Look for signs of damage, corrosion, or loose connections

4. Ensure that the wiring is not pinched, frayed, or exposed to heat sources

5. Test the Fuel Temperature Sensor

6. Use a multimeter to test the resistance of the fuel temperature sensor. Compare the readings to the specifications provided in the vehicle's service manual

7. If the sensor is out of specification, it may need to be replaced

8. Check the Sensor Circuit

9. With the multimeter, check the voltage at the sensor connector with the ignition on (engine off). You should see a reference voltage (usually around 5V)

10. If the voltage is low or absent, trace the circuit back to the engine control module (ECM) to identify any breaks or shorts

11. Inspect the ECM

12. If the sensor and wiring are in good condition, the issue may lie with the ECM itself. Check for any software updates or known issues with the ECM for your vehicle model

13. In some cases, reprogramming or replacing the ECM may be necessary

14. Check for Fuel System Issues

15. Ensure that the fuel system is functioning properly. Low fuel pressure or other fuel delivery issues can sometimes trigger sensor codes

16. Inspect the fuel pump, fuel filter, and fuel lines for any blockages or malfunctions

17. Clear the Codes and Test Drive

18. After performing repairs or replacements, clear the trouble codes using the OBD-II scanner

19. Take the vehicle for a test drive to see if the code returns. Monitor the fuel temperature readings if your scanner allows it

20. Consult a Professional

21. If you are unable to resolve the issue after these steps, it may be best to consult a professional mechanic who has experience with your specific vehicle make and model. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the P0187 code