Fuel Temperature Sensor B Circuit Range/Performance
The engine computer detected that the fuel temperature sensor B is reading outside its normal range or not responding correctly. Think of it like a thermometer that's either broken or giving wildly inaccurate temperature readings.
The ECU monitors voltage from fuel temperature sensor B to track fuel temperature for precise fuel injection timing and quantity adjustments. The sensor should produce a voltage signal that varies linearly with temperature changes. If the signal stays constant, drops to zero, or exceeds expected voltage thresholds, the ECU logs a fault.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Sensor Voltage | 0.5-4.5V varying with temperature | Out of range, stuck value, or erratic fluctuation |
| Temperature Reading | -40°C to 125°C (-40°F to 257°F) | Implausible rate of change or static reading |
Code P0187 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P0187 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.