P2BAB
NOx Exceedence — Reagent System Performance
The SCR system has detected that NOx emissions exceed the legal limit and the cause is traced to a performance fault in the reagent dosing system — for example a slow dosing pump, a clogged injector, or a frozen line that is not yet caught by another DTC.
The SCR system has detected that NOx emissions exceed the legal limit and the cause is traced to a performance fault in the reagent dosing system — for example a slow dosing pump, a clogged injector, or a frozen line that is not yet caught by another DTC.
Common causes
- high
Reductant injector clogged with crystals
One of the most commonly reported causes for this code — check this first.
Typical part cost: $220-1650
- medium
Dosing pump output below spec
A plausible cause — test and verify before replacing parts.
Typical part cost: $220-1650
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First things to check
- 1Confirm the code with a scan tool and check for additional related codes.
- 2Inspect the relevant sensors, wiring, and connectors for damage or corrosion.
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Related codes
See related trouble codes
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Frequently asked questions
What does P2BAB mean?
P2BAB means "NOx Exceedence — Reagent System Performance". It is a generic OBD-II code that points to a fault in the auxiliary emission controls.
What are the most common causes of P2BAB?
reductant injector clogged with crystals; dosing pump output below spec; reagent supply line blocked — these are the most commonly reported causes. Verify with a proper diagnosis before replacing parts, or use the Wrenchify app for a vehicle-specific diagnosis.
Can I keep driving with this code?
This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly. Use the Wrenchify app for a full diagnosis specific to your vehicle.
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