12 documented codes across 42 real diagnostics.
NOx after-treatment: reductant dosing, NOx sensors, SCR catalyst efficiency. Distinct from the DPF even though both live in the exhaust.
Ranked by how often we actually see them
- P20EE, SCR NOx catalyst efficiency below threshold, bank 1
- P2BA9, not individually documented
- P20E8, not individually documented
- P2BAF, not individually documented
- P204B, not individually documented
- P229E, not individually documented
- P220A, not individually documented
- P2BAE, not individually documented
- P220E, not individually documented
- P2202, NOx sensor circuit range/performance, bank 1
- P2203, NOx sensor circuit high, bank 1
- P2043, Reductant tank temperature sensor circuit