EVAP Fuel Vapor Temperature Sensor Circuit High Voltage
Diagnostic trouble code P2027 indicates that the powertrain control module (PCM) has detected a high voltage condition in the evaporative emissions (EVAP) fuel vapor temperature sensor circuit. This typically means the sensor's signal voltage has exceeded the maximum expected threshold, often pointing to an open circuit or a faulty sensor.
This code primarily affects the vehicle's emissions system and will not cause immediate drivability issues. However, it should be diagnosed and repaired to ensure proper EVAP system operation and to pass emissions testing.
Common symptoms
- Illuminated Check Engine Light
- Failure to pass an emissions test
- Slight decrease in fuel efficiency
- Faint fuel odor near the vehicle (rare)
- No noticeable drivability symptoms
Likely causes
- Faulty EVAP fuel vapor temperature sensor
- Open or shorted wiring in the sensor circuit
- Corroded or damaged electrical connector at the sensor
- Poor ground connection in the EVAP sensor circuit
- Faulty Powertrain Control Module (PCM) (rare)
What to check before replacing parts
Visually inspect the EVAP fuel vapor temperature sensor wiring and connector.
Look for: Look for broken wires, chafing, melted insulation, or severe corrosion inside the connector that could cause an open circuit or high resistance.
Scan for other EVAP system codes.
Look for: Check if other EVAP codes are present, which might indicate a shared ground issue or a broader wiring harness problem.
Measure the reference voltage at the sensor connector with a multimeter.
Look for: With the key on and engine off, verify that the PCM is supplying the correct reference voltage (usually 5 volts). If voltage is missing or too high, trace the wiring back to the PCM.
Test the resistance of the EVAP fuel vapor temperature sensor.
Look for: Compare the sensor's resistance reading at the current ambient temperature to the manufacturer's specifications. An infinite reading (OL) indicates an internal open in the sensor.
Check the ground circuit for the sensor.
Look for: Measure the resistance between the sensor ground pin and a known good chassis ground. High resistance indicates a poor ground connection causing the high voltage reading.
This page explains the generic P2027 definition and is general reference information, not a diagnosis for your specific vehicle. Actual causes, severity, and repairs vary by make, model, engine, and mileage — always confirm with a scan tool and a qualified technician before replacing parts.
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