The P0187 OBD2 fault code indicates that the engine control module (ECM/PCM) has detected a lower-than-expected signal from the Fuel Temperature Sensor B circuit. This sensor provides fuel temperature information to the engine management system, helping it make appropriate fuel-related calculations. A low signal can be caused by a faulty sensor, damaged wiring, a short circuit, or an electrical connection problem.
What does the engine code P0187 mean?
The engine code P0187 means that the ECM/PCM has detected a low voltage condition in the Fuel Temperature Sensor B circuit. The code does not automatically mean that the sensor itself is defective. Wiring, connectors, power supply, ground, or a short circuit can also cause P0187.
Fault Code Description
Code: P0187
Definition: Fuel Temperature Sensor "B" Circuit Low
Type: Generic OBD2 Trouble Code
System: Fuel and Engine Management
P0187 is a generic OBD2 powertrain code. It can appear on vehicles from many manufacturers, but the sensor location, circuit design, connector configuration, and diagnostic procedure may differ between models.
Symptoms of P0187
- Check Engine Light is illuminated.
- Hard or extended engine starting.
- Rough or unstable engine idle.
- Engine hesitation during acceleration.
- Reduced engine performance.
- Increased fuel consumption.
- Incorrect fuel temperature readings in live data.
- In some vehicles, there may be no noticeable symptoms.
Common Causes of P0187
- Faulty Fuel Temperature Sensor B.
- Short to ground in the sensor signal circuit.
- Damaged or broken sensor wiring.
- Loose or damaged electrical connector.
- Corroded or contaminated terminals.
- Faulty sensor reference or power circuit.
- Poor electrical ground.
- Wiring damaged by heat, vibration, or friction.
- ECM/PCM fault in rare cases.
P0187 on Honda, Nissan, and Dodge Vehicles
The P0187 code can be encountered on different vehicle brands, including Honda, Nissan, and Dodge. These manufacturers are examples only, and the exact Fuel Temperature Sensor B design can vary significantly between models and engines.
Honda
On some Honda applications, the fuel temperature sensing circuit may be integrated into a larger fuel-system component. When diagnosing P0187, the sensor location and circuit should be confirmed using the correct wiring diagram for the specific Honda model and engine.
Nissan
On some Nissan vehicles, fuel temperature information can be part of the fuel-management system. A proper diagnosis should include checking the sensor signal, connector, wiring, ground, and live-data readings before replacing any component.
Dodge
On some Dodge applications, the fuel temperature sensor circuit and its location can differ depending on the engine and fuel system. The manufacturer's wiring diagram and service specifications should be used to identify the correct circuit before testing or replacing the sensor.
These brands are provided only as examples. P0187 does not use the same sensor location or wiring configuration on every Honda, Nissan, or Dodge vehicle.
P0187 Severity
Severity: Moderate. P0187 should be diagnosed promptly because an incorrect fuel temperature signal can affect engine management and fuel-related calculations.
Some vehicles may continue to operate normally, while others may experience hard starting, hesitation, poor fuel economy, or reduced engine performance.
Average Repair Cost
The repair cost for P0187 depends on the vehicle and the actual cause of the low sensor signal. Typical estimated costs include:
- Diagnostic testing: $50–$150
- Fuel temperature sensor replacement: $100–$300
- Wiring repair: $80–$250
- Connector repair or replacement: $80–$200
- ECM/PCM repair or replacement: $500–$1,500+
These are general estimates only. Actual costs depend on the vehicle model, engine, sensor location, parts availability, and local labor rates.
How to Diagnose P0187
1. Scan for Trouble Codes
Use an OBD2 scanner to check for P0187 and any additional stored or pending trouble codes. Related fuel-system codes can help identify the source of the problem.
2. Check Fuel Temperature Live Data
Monitor the Fuel Temperature Sensor B reading using a scan tool. Compare the displayed temperature with the actual fuel temperature and surrounding conditions.
3. Inspect the Sensor Connector
Check the connector for corrosion, loose terminals, damaged pins, moisture, or poor electrical contact.
4. Inspect the Wiring
Inspect the wiring harness for broken wires, damaged insulation, chafing, heat damage, and signs of previous incorrect repairs.
5. Check for a Short to Ground
Because P0187 indicates a low circuit signal, check the signal wire for an unintended connection to ground. Use the manufacturer's wiring diagram and testing specifications for the vehicle.
6. Test the Sensor
Test Fuel Temperature Sensor B according to the manufacturer's specifications. If the sensor produces an incorrect resistance or signal for the actual fuel temperature, it may need replacement.
7. Clear the Code and Retest
After repairing the confirmed problem, clear the diagnostic code and perform a road test. Recheck the live data and verify that P0187 does not return.
Common Repairs for P0187
- Replace the faulty Fuel Temperature Sensor B.
- Repair damaged or broken wiring.
- Repair a short-to-ground condition.
- Repair or replace damaged connectors.
- Clean corroded electrical terminals.
- Repair the sensor ground or reference circuit.
- Secure wiring away from heat and vibration.
- Repair or replace the ECM/PCM only after confirming that the sensor and wiring are functioning correctly.
Common Diagnostic Mistakes
- Replacing the sensor without testing the circuit.
- Assuming P0187 always means the sensor is defective.
- Ignoring a possible short to ground.
- Failing to inspect the connector and wiring.
- Using the wrong wiring diagram for the vehicle.
- Assuming Honda, Nissan, and Dodge use the same sensor configuration.
- Replacing the ECM/PCM before proving it is faulty.
- Ignoring additional stored trouble codes.
Can You Drive With P0187?
The vehicle may remain drivable if it starts and operates normally, but P0187 should be diagnosed as soon as possible. An incorrect fuel temperature signal can affect engine operation and fuel economy.
If the vehicle develops severe hesitation, stalling, major starting problems, or significant loss of power, it should be inspected before continued driving.
Related OBD2 Codes
- P0180 – Fuel Temperature Sensor "A" Circuit
- P0181 – Fuel Temperature Sensor "A" Circuit Range/Performance
- P0182 – Fuel Temperature Sensor "A" Circuit Low
- P0183 – Fuel Temperature Sensor "A" Circuit High
- P0184 – Fuel Temperature Sensor "A" Circuit Intermittent
- P0185 – Fuel Temperature Sensor "B" Circuit
- P0186 – Fuel Temperature Sensor "B" Circuit Range/Performance
- P0187 – Fuel Temperature Sensor "B" Circuit Low
- P0188 – Fuel Temperature Sensor "B" Circuit High
- P0189 – Fuel Temperature Sensor "B" Circuit Intermittent
FAQ
What does the engine code P0187 mean?
P0187 means the ECM/PCM has detected a lower-than-expected voltage signal in the Fuel Temperature Sensor B circuit.
Is P0187 a generic OBD2 code?
Yes. P0187 is a generic OBD2 powertrain code, although the exact sensor location and circuit design vary between vehicle manufacturers and models.
Does P0187 mean the fuel temperature sensor is bad?
Not necessarily. A short to ground, damaged wiring, poor connector, faulty reference circuit, or ground problem can also cause P0187.
Can P0187 cause poor fuel economy?
Yes. An incorrect fuel temperature signal can affect engine-management calculations and may contribute to increased fuel consumption.
Can Honda vehicles have P0187?
Yes. Honda is one example of a manufacturer where P0187 may be encountered. The exact diagnostic procedure depends on the specific Honda model and engine.
Can Nissan vehicles have P0187?
Yes. Nissan is another example. The sensor location and circuit configuration should be confirmed using the correct service information for the specific vehicle.
Can Dodge vehicles have P0187?
Yes. Dodge vehicles can also encounter P0187, but the exact fuel temperature sensor arrangement depends on the model and engine.
How do I fix P0187?
The correct repair depends on the diagnosis. Common repairs include replacing the Fuel Temperature Sensor B, repairing wiring or connectors, correcting a short-to-ground condition, or repairing the sensor's reference or ground circuit.
Is P0187 serious?
P0187 is generally considered a moderate-severity fault. It may not cause immediate engine damage, but it should be diagnosed because it can affect engine operation and fuel management.
Conclusion
The P0187 OBD2 fault code indicates a low signal condition in the Fuel Temperature Sensor B circuit. Common causes include a faulty sensor, shorted wiring, damaged connectors, poor grounding, or another electrical circuit problem. Honda, Nissan, and Dodge are examples of vehicle brands where this code may be encountered, but the exact sensor location and circuit design can vary by model and engine. Always use the correct manufacturer-specific wiring diagram and specifications when diagnosing P0187.