OBD-II code P2027 means the powertrain control module (PCM) has detected an abnormally high voltage signal from the evaporative emissions (EVAP) fuel vapor temperature sensor. This sensor is a thermistor that reports the temperature of fuel vapor or of the EVAP canister, and an open circuit in the sensor, its wiring, or connector is the usual reason the signal reads abnormally high.
A broken, chafed, stretched, or disconnected signal or ground wire, or corroded connector pins, is the most common cause. An open circuit lets the signal line float up to the reference voltage, producing the high reading the PCM reports.
The sensor is a thermistor and can fail open internally, sending its resistance to infinity. The PCM then sees the full reference voltage and sets P2027.
Moisture, road salt, and oxidation at the sensor connector interrupt the circuit and produce the same high-voltage symptom as a physically broken wire.
If the vapor temperature sensor shares a ground splice or ground point with other EVAP components, a break in that path can float the sensor signal high.
Less common, but damaged insulation on the signal wire contacting a powered circuit will hold the sensor signal high even when the sensor is good.
The powertrain control module is a rare cause of P2027 and should be considered only after the sensor, harness, and connectors have all been tested and verified good.
Yes, in most cases. P2027 is an emissions system code and usually does not affect drivability, fuel economy, or safety. The vehicle will run normally, but the Check Engine Light will remain on and the vehicle will typically fail an emissions or smog inspection.
Not directly. P2027 is specific to the fuel vapor temperature sensor circuit, not the fuel filler cap or a general EVAP leak. A loose or leaking gas cap more commonly produces codes such as P0455 or P0442 rather than P2027.
No. The PCM is one of the least likely causes of P2027. The overwhelming majority of these codes are caused by the sensor itself, an open in its wiring, or a corroded connector. Replacing or reprogramming the PCM before the sensor and harness are fully tested is almost always an unnecessary and incorrect repair.
The general meaning — a high-voltage reading from the EVAP fuel vapor temperature sensor circuit — is consistent across manufacturers, but sensor location, connector pin assignments, wire colors, and exact resistance and voltage specifications vary. Always consult the vehicle-specific service information for the correct values and test points.