Fuel Temp Sensor High Voltage
The P1186 code indicates that the powertrain control module (PCM) has detected an abnormally high voltage signal from the fuel temperature sensor (FTS) or the high-pressure fuel system monitoring circuit. This typically points to an open circuit, a short to battery voltage, or a faulty sensor reporting extremely high fuel temperature (or high pressure, depending on the variant). As a result, the PCM cannot properly compensate the air-fuel mixture, potentially affecting engine performance and emissions.
01. Most Common Causes
- Faulty fuel temperature sensor (internal open circuit)
- Sensor wiring or connectors shorted to battery voltage (B+)
- Open sensor signal circuit (broken wire or disconnected connector)
- Internal PCM failure (rare)
- Fuel return system issues causing actual fuel overheating
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor fuel economy or rough idle
03. Step-by-Step Diagnosis
Scan for additional codes and freeze frame data
Visually inspect the fuel temperature sensor connector and wiring for damage, corrosion, or shorts
Measure sensor resistance and compare to manufacturer specifications; replace if out of range
Check for battery voltage on the signal wire with the sensor disconnected; repair short if present
If all else is normal, test PCM output or replace PCM as a last resort
1. Frequently Asked Questions
Is it safe to drive?▼
Yes, but you may experience reduced fuel economy and performance. It's best to diagnose and repair soon to prevent potential drivability issues.
How much does it cost to fix?▼
Typically $100–$300 for sensor replacement, including parts and labor. Wiring repairs may cost less, while PCM replacement can exceed $800.