DPF Issues with 2014 NPR

Michael Mobile Technician Utah Posted   Latest   Edited  
Case Study
2014 Isuzu NPR-HD 5.2L (6 4HK1)
No Codes
Instument Panel Dpf Warnings

I was asked to take a look at an NPR Box Truck. The shop had replaced a plugged DPF filter. There were DPF warning lamps turned on in the instrument panel. I connected a TEXA scan tool to the vehicle. There were two resets that I tried. The first was the DPF reset and the second the PCM learned values reset. I could see that the data cleared and set everything to zero. The lights persisted. I attempted both the standard and long tool driven REGEN. The temp did not get over 575 F. I suggested to the shop that the 7th injector was not spraying enough fuel to get the DPF hot. They took it out and decided to replace rather than clean it. I went back again started the REGEN. The temp raised to 1100 F. The REGEN ran and finished. Soot value 0mg. Still the lights persisted. I was hoping a forced regen would take care of them. No such luck. I contacted an Engineer at TEXA to ask about the issue. He stated that there is a TSB within the TEXA software. It explains that on … NPR vehicles the PCM needs to be reflashed to turn off the lights. The customer drove too long without addressing REGEN problem. According to the TSB an update will turn off the lights. I am waiting to hear from the shop on whether the reflash worked. 

Allan Instructor

Thanks for this information Michael, in the automotive world we have access to TSBs and recalls from several sources. Is there a resource for medium and heavy duty that would list this TSB? Do you know if this TSB was something TEXA came up with or if it was issued by the manufacturer? Don’t do medium/heavy duty so not familiar with information availability. Thanks.

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Michael Mobile Technician

It looked like an official Isuzu release. Mitchell has some MD and HD resources. Not sure about anyone else. Agricultural machine manuals are even harder to find.

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Matthew Mobile Technician

Thanks for the tip. BTDT with some Cummins engines.

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