Evaporative Emissions (EVAP) Fuel Vapor Temperature Sensor Circuit High Voltage
The P2027 code indicates the engine control module detected a high voltage condition in the EVAP fuel vapor temperature sensor circuit. This sensor monitors the temperature of fuel vapors in the charcoal canister to optimize emissions control, and an out-of-range signal suggests either a sensor failure or wiring issue.
What You Might Notice
- Check Engine Light (CEL) illuminated
- Failed emissions test
- Slight decrease in fuel economy
- Fuel odor near fuel tank or filler area
- Difficult or prolonged fuel pump nozzle engagement at gas pump
Most Common Causes
- 1
Defective EVAP fuel vapor temperature sensor
The sensor itself has failed or drifted out of calibration, causing it to send an abnormally high voltage signal to the ECM.
- 2
Wiring harness damage or corrosion
The sensor wiring is corroded, pinched, or damaged, creating excessive resistance or allowing the signal wire to short to power.
- 3
Connector or pin issues
The connector at the sensor or ECM is corroded, melted, has a broken lock tab, or pins are misaligned, disrupting the circuit.
- 4
Engine Control Module (ECM) failure
The ECM's sensor input circuit has malfunctioned, causing it to misinterpret normal sensor readings as high voltage.
How to Diagnose It
- 1
Check Defective EVAP fuel vapor temperature sensor — The sensor itself has failed or drifted out of calibration, causing it to send an abnormally high voltage signal to the ECM.
- 2
Check Wiring harness damage or corrosion — The sensor wiring is corroded, pinched, or damaged, creating excessive resistance or allowing the signal wire to short to power.
- 3
Check Connector or pin issues — The connector at the sensor or ECM is corroded, melted, has a broken lock tab, or pins are misaligned, disrupting the circuit.
- 4
Check Engine Control Module (ECM) failure — The ECM's sensor input circuit has malfunctioned, causing it to misinterpret normal sensor readings as high voltage.
How to Fix It
- 1
Replace EVAP fuel vapor temperature sensor
Locate the sensor on or near the charcoal canister, disconnect the wiring harness, remove the old sensor, and install a new OEM or quality replacement sensor. Clear the code and test.
- 2
Inspect and repair wiring harness
Trace the sensor wiring from the connector to the ECM for visible damage, corrosion, or pinching. Repair damaged sections by splicing with appropriate gauge wire and heat shrink tubing, or replace the entire harness if severely compromised.
- 3
Clean or replace connectors and pins
Remove corrosion from connector pins using electrical contact cleaner and a soft brush, or replace the connector assembly if pins are melted or broken. Ensure proper seating of all connections.
- 4
Test and replace ECM if necessary
After confirming the sensor and wiring are good, use a diagnostic scanner to monitor the sensor voltage in real-time. If readings remain abnormal, the ECM input circuit may be faulty and require ECM replacement or reprogramming by a qualified technician.
Need a deeper diagnosis?
Search for related repair guides or browse by system.