Cause
Faulty EVAP purge valve
The valve drawing stored fuel vapour into the engine. Stuck open it is an unmetered vacuum leak that only exists when the engine is running, giving a rough idle and lean codes that no visual inspection of the intake will explain. Stuck shut, the system simply fails its leak test.
Typically an easy fix. Often worth checking before paying anyone to look.
Codes this can cause (12)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0440 Evaporative Emission System Malfunction Likely for this code Low
- P0441 Evaporative Emission System Incorrect Purge Flow Likely for this code Low
- P0443 Evaporative Emission System Purge Control Valve A Circuit Likely for this code Low
- P0496 Evaporative Emission System High Purge Flow Likely for this code Low
- P0497 Evaporative Emission System Low Purge Flow Likely for this code Low
- P2178 System Too Rich Off Idle Bank 1 Likely for this code Moderate
- P2188 System Too Rich at Idle Bank 1 Likely for this code Moderate
- P014B O2 Sensor Delayed Response - Lean to Rich Bank 2 Sensor 2 Moderate
- P0466 Evaporative Emission Purge Flow Sensor Circuit Range/Performance Low
- P0507 Idle Air Control System RPM Higher Than Expected Moderate
- P2180 System Too Rich Off Idle Bank 2 Moderate
- P2190 System Too Rich at Idle Bank 2 Moderate
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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