A/C On During KOER Test
The P1464 code indicates that the Powertrain Control Module (PCM) detected the air conditioning (A/C) clutch was engaged during the Key On Engine Running (KOER) self-test. This test requires all accessories to be off to properly evaluate engine and transmission performance. The A/C request signal from the climate control module to the PCM was active, preventing the test from completing or causing a fault. This is often due to driver error (A/C left on) or a stuck A/C clutch relay or switch.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- KOER test aborted or fails to complete
- A/C compressor runs continuously
- Engine may run rough or stall during test
2. Most Common Causes
- Blocked or failed EVAP purge valve
- Blocked or failed canister vent valve (CVS)
- Damaged or poorly sealing fuel cap
- EVAP vapor lines blocked, pinched, or disconnected
- Clogged canister air filter
- Fuel tank pressure (FTP) sensor reading incorrectly
- Damaged fuel tank or leaking welds
- Loose or deteriorated EVAP hose connections
3. Step-by-Step Diagnosis
Step 1: Ensure A/C is off and retry KOER test
Step 2: Check for stuck A/C clutch relay; test relay operation
Step 3: Inspect A/C request signal circuit for shorts or opens
Step 4: Verify climate control module output with scan tool
4. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, but the A/C may not operate correctly and the check engine light will remain on. It is safe to drive short distances, but have it diagnosed soon.
How much does it cost to fix?▼
Typically $50-$150 for diagnosis and repair, which may include replacing a relay or repairing a wiring issue.
5. Commonly Affected Makes
This is a manufacturer-specific code. The exact manufacturer is not confirmed in our current database.