P2AB4 Cold Start Intake Manifold Runner Control Stuck Open Bank 2

P2AB4 is the bank 2 version of the open-stuck check during cold start, so it only appears on engines with a separate runner control for each cylinder bank, typically V or flat engines. The runner flaps of the second bank fail to leave their open position as long as the cold-start routine runs, so that bank burns its mixture with less charge motion than intended. No manufacturer documents P2AB4 publicly; the requirement comes from CARB's cold-start component monitoring, which only applies once the engine has been off for six hours or longer. Ford's 2020 to 2023 gasoline summary shows the conventional split for vacuum-actuated V engines, with P2004 for bank 1 and P2005 for bank 2. Comparing bank 2 with bank 1 helps: if only one side lags, look at that actuator, its vacuum line and its linkage. Bank 1 is P2AB3.

Likely causes

Symptoms

• Check engine light on
• Uneven running between the banks shortly after a cold start
• Higher cold-start emissions

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, fordservicecontent.com.