P23A4 — Exhaust heat-exchanger bypass valve B control circuit — high electrical level

P23A4 concerns exhaust heat-exchanger bypass valve B control circuit. The monitor reports an electrical level above its expected range. The high finding belongs to the valve-control circuit. It does not directly measure exhaust-gas temperature or heat-exchanger efficiency.

Affected system: Exhaust heat-exchanger 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: P23A4-00, P23A400 (some scan tools add the fault-type byte, e.g. -00).