P2BAC
NOx Exceedence - Insufficient Reagent Quality
The diesel exhaust aftertreatment system detects elevated NOx levels combined with abnormal reagent (AdBlue/DEF) consumption, indicating that the reagent quality is insufficient or contaminated. Many regions trigger driver inducement (limited restarts).
The diesel exhaust aftertreatment system detects elevated NOx levels combined with abnormal reagent (AdBlue/DEF) consumption, indicating that the reagent quality is insufficient or contaminated. Many regions trigger driver inducement (limited restarts).
Common causes
- high
Non-DEF liquid in tank (water, diesel)
One of the most commonly reported causes for this code — check this first.
Typical part cost: $220-2200
- medium
Aged or diluted DEF/AdBlue
A plausible cause — test and verify before replacing parts.
Typical part cost: $220-2200
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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 P2BAC mean?
P2BAC means "NOx Exceedence - Insufficient Reagent Quality". It is a generic OBD-II code that points to a fault in the auxiliary emission controls.
What are the most common causes of P2BAC?
non-def liquid in tank (water, diesel); aged or diluted def/adblue — 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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