P208B — Reductant pump A control — performance fault or stuck inactive

P208B concerns reductant pump A control. The monitor reports unsuitable control performance or a control function that remains inactive. The definition combines a performance problem with a possible inactive state. It does not identify the pump itself as the confirmed failed part.

Affected system: Reductant dosing and SCR aftertreatment

Symptoms

• An emissions or engine warning may appear.
• Some vehicles may lose power or impose SCR-related restrictions if the fault persists.

Possible causes

• Reductant pump A may not deliver the expected response or pressure when controlled.
• A failing pump, damaged wiring or corroded connectors can contribute.
• A controller-related fault is considered after the electrical and pump checks.

What to check

• Read P208B and related SCR codes; check the DEF level and inspect pump connections.
• Use a compatible scan tool to command the pump and observe its response, if supported.
• Check electrical inputs and pump output against the vehicle service procedure before replacing components.

Also written as: P208B-00, P208B00 (some scan tools add the fault-type byte, e.g. -00).