P236D — Cylinder 12 pressure variation — variation too low

P236D concerns cylinder 12 pressure variation. The monitor reports less pressure variation than expected for the named cylinder. This is a pressure-variation finding, which is distinct from a low electrical signal in a pressure-sensor circuit.

Affected system: Cylinder-pressure monitoring

Symptoms

• Warning light may illuminate
• Related system function may be impaired
• Vehicle-specific symptoms vary

Possible causes

• Mechanical timing or operating issue, sensor or actuator fault, connector 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
• Record freeze-frame conditions; compare relevant live data and inspect mechanical operation, wiring and related fault codes before replacing parts.
• Confirm measured values against the vehicle service information
• Retest under the conditions that set the code
• Record freeze-frame conditions; compare relevant live data and inspect mechanical operation, wiring and related fault codes before replacing parts.
• Repair the verified cause and confirm the code does not return

Also written as: P236D-00, P236D00 (some scan tools add the fault-type byte, e.g. -00).