Powertrain, generic (extended)

P2028 EVAP Fuel Vapor Temperature Sensor Circuit Intermittent

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modeNo

P2028 covers a vapor temperature signal that jumps or briefly drops out instead of changing smoothly, as vapor temperature normally does. Public manufacturer documentation for it is lacking: Ford's 2014 list ends with P2027, and the Audi bulletins concern P2024–P2026 only. The nearest documented case is Audi's sensor inside leak detection unit J909, mounted at the canister near the rear wheel arch where water and road salt reach the connector. CARB requires input components used by the EVAP monitor to be checked for circuit faults, which leaves room for a separate intermittent code. Suspects are a loose or corroded plug, a wire chafing on the body or tank straps, or moisture inside the leak detection unit. The lamp may come and go between trips.

Likely causes

Corroded or loose connector at the canister area
Wire chafing against body or tank straps
Moisture inside the leak detection unit with integrated sensor

Symptoms

  • Warning lamp that switches on and off
  • EVAP readiness slow to complete

Repair estimate

DifficultyMediumDIY possible
Parts and labour€20–400
Time0.5–2.5 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

evap fuel vapor temp sensorevap harness

Related codes

P2024P2026P2027

References: law.cornell.edu, static.nhtsa.gov.