P2027

Code

Generic P — Powertrain

EVAP Fuel Vapor Temperature Sensor Circuit High Voltage

Brand: Generic

Type: P — Powertrain

Views: UK: 24 EN: 27 RU: 27

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Page language: EN

Malfunction Indicator Lamp (MIL) / Check Engine Light illuminated
Possible EVAP system disabled or limp EVAP operation
Failed emissions test or readiness monitor set to NOT READY
No noticeable drivability issues in many cases (fault is sensor circuit related)
Unusual EVAP purge behavior or stored EVAP-related faults

Read freeze frame and live data with a scan tool (verify sensor voltage/temperature reading)
Inspect sensor connector and harness for corrosion, damage, water or fuel contamination
Back-probe and measure sensor signal voltage with key ON, engine OFF
Measure sensor resistance vs. ambient temperature at the sensor (disconnect sensor)
Check for 5V reference and ground at the sensor connector (if applicable)
Wiggle harness while monitoring live data to reproduce intermittent faults

Typical sensor signal: approximately 0.5–4.5 V range (varies by vehicle); exact spec in OEM manual
Open-circuit or short-to-reference typically reads near reference/battery voltage (e.g., ~5 V) — register as 'high voltage'
Short-to-ground reads near 0 V (would register as 'low voltage')
Thermistor resistance varies with temperature (NTC sensor: resistance decreases as temperature rises) — consult OEM resistance-vs-temperature table
Stable steady voltage expected; noisy or intermittent voltage indicates wiring or connector issues

Retrieve and record all EVAP-related codes and freeze-frame data with a scan tool; note sensor voltage/temperature value when the code set.
Perform a visual inspection of the sensor, connector, and harness. Repair any obvious physical damage, corrosion, or contamination.
With key ON (engine OFF), back-probe the sensor connector and measure the signal wire voltage. Compare to expected range. If signal is high (near reference voltage), suspect open/short-to-voltage.
Disconnect the sensor and measure its resistance at known ambient temperature. Compare to the OEM resistance table. An open or out-of-spec reading indicates a bad sensor.
Check for 5V reference (or manufacturer-specified reference) and good ground at the connector. If reference missing, trace to ECM and repair power/reference supply.
Perform continuity checks from the sensor connector to the ECM input to find opens or short-to-power. Repair/replace wiring as needed.
If wiring and sensor test good, substitute a known-good sensor (if available) or inspect/replace the ECM connector. Replace ECM only after exhausting wiring and sensor tests.
After repairs, clear codes, perform readiness/EVAP tests and road test to confirm code does not return.

⚠️ Status

EVAP Fuel Vapor Temperature Sensor Circuit High Voltage

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours

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