P2000: Early Cummins NOx-efficiency fault with soot-fouled oxygen sensors

Efficiency wording does not isolate the NOx absorber

P2000 means NOx absorber efficiency below threshold, bank 1, in this older Cummins application. The bulletin connects the complaint with oxygen-sensor fouling and may also involve P2A00 or P2A01. It requires addressing excessive soot and associated service updates before sensor work. This gives a reason to investigate the conditions influencing the efficiency assessment before assuming the absorber itself must be replaced.

Existing sensor insulation determines whether this path applies

The technician checks whether the front oxygen-sensor wrap or blanket is already correctly installed and undamaged. If it is, the bulletin says its repair will not address the condition and directs normal diagnosis. For eligible vehicles requiring the repair, the procedure installs the specified sensor heat shield and inspects both oxygen sensors. Earlier sensors are replaced; the later design can be identified by its part marking or soot-shield shape shown in the source.

Cleaning has a narrow manufacturer-approved method

Reusable sensors are cleaned with shop air only; the bulletin specifically excludes solvents and chemical cleaners. It also calls for checking maintenance, crankcase-ventilation restriction and causes of excess soot, rather than repeatedly cleaning a sensor while contamination continues. Ask the shop to record the existing wrap condition, sensor design and reason for soot accumulation. This is a historical emissions repair for a tightly defined diesel application, not permission to remove emissions equipment or apply the same cleaning method to every oxygen sensor.

Source and applicability

Chrysler bulletin 25-001-13, January 2013: specified 2007–2010 Ram 2500/3500 platforms with 6.7 L ETJ Cummins diesel, built before August 2, 2009. Check the listed platform and production date together.

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