P20F8 reports an intake-runner control performance fault on bank 1. The definition does not establish that the runners are stuck open or closed.
Meaning, symptoms, causes and checks
P20F8 concerns intake-manifold runner control circuit, bank 1. The monitor reports that the named control function does not meet its expected operating behavior. The monitor reports circuit/control performance. This wording does not establish that the runners are stuck specifically open or closed.
Affected system: Intake-manifold airflow control
Symptoms
- Warning light may illuminate
- Related system function may be impaired
- Vehicle-specific symptoms vary
Possible causes
- Implausible sensor or switch signal, poor ground, connector corrosion, or wiring damage
- Related wiring, connector, power or ground fault
- Vehicle-specific mechanical or control issue
What to check
- Record stored and pending codes and freeze-frame data
- Compare the named sensor or switch signal with actual operating conditions; inspect the connector, reference supply, ground and harness.
- Confirm measured values against the vehicle service information
- Retest under the conditions that set the code
- Compare the named sensor or switch signal with actual operating conditions; inspect the connector, reference supply, ground and harness.
- Repair the verified cause and confirm the code does not return
Also written as: P20F8-00, P20F800 (some scan tools add the fault-type byte, e.g. -00).