P2028: EVAP Fuel Vapor Temperature Sensor Circuit Intermittent

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.

Low severity. Can I keep driving?Yes, you can normally keep driving. If there is a strong smell of gasoline, find the leak before continuing and do not smoke nearby.

Symptoms

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

Most 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

What to check, in order

Start with the simplest. You can tick off each step.

Start with the fuel cap: tighten it fully and check its seal
Gently move the wiring with the engine running and watch whether the reading changes.
Inspect the hoses and connections around the tank and the charcoal canister
Use the scanner to test the purge and vent solenoid valves
Run a smoke test to find small leaks

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P2028 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
0: Subsystem depends on the code range
28: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2028?

Yes, you can normally keep driving. If there is a strong smell of gasoline, find the leak before continuing and do not smoke nearby.

What causes code P2028?

The most common causes are: corroded or loose connector at the canister area; wire chafing against body or tank straps; moisture inside the leak detection unit with integrated sensor.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.