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2012 Isuzu NPR-HD Catalytic Converter and DPF Issue

J

jon chelton

New Recruit
Owner/Operator
Hi,

I have a 2012 Isuzu NPR-HD with approx 90k miles and am having issues with DPF regen and Catalytic Converter. First off when driving highways speeds, it does a regen about every 125-150 miles. If there is no traffic and moving ok, there is no issues. If stuck in any stop and go traffic, when attempting to regen while driving it fails and MIL light comes on (usually with reduced power light which goes away when turn off and on) with code P0420 (Catalyst System Efficiency Below Threshold).
When MIL light is on, it does not attempt a regen while driving and manual regen does not seem to work until code is cleared. This issue has happened 3 times in 1 month, the first time was when truck was about 5 hours away, he drove home and it also had code P2463 (Diesel Particulate Filter Differential Pressure Too Low), but that did not occur the next 2 times the MIL light came on.

Any thoughts?

Thanks for the help!
 
T

Treadmill

Veteran Expediter
Owner/Operator
jon chelton said:
Hi,

I have a 2012 Isuzu NPR-HD with approx 90k miles and am having issues with DPF regen and Catalytic Converter. First off when driving highways speeds, it does a regen about every 125-150 miles. If there is no traffic and moving ok, there is no issues. If stuck in any stop and go traffic, when attempting to regen while driving it fails and MIL light comes on (usually with reduced power light which goes away when turn off and on) with code P0420 (Catalyst System Efficiency Below Threshold).
When MIL light is on, it does not attempt a regen while driving and manual regen does not seem to work until code is cleared. This issue has happened 3 times in 1 month, the first time was when truck was about 5 hours away, he drove home and it also had code P2463 (Diesel Particulate Filter Differential Pressure Too Low), but that did not occur the next 2 times the MIL light came on.

Any thoughts?

Thanks for the help!
Click to expand...
Hey Jon we have a resident mechanic by the name greasytshirt. PM him your situation (cut and paste) your OP and you should get a quicker response.
 
greasytshirt

greasytshirt

Moderator
Staff member
Mechanic
It kind of sounds like it's asking for a manual regen (I'm not as proficient with Isuzu). You'll have to park for about 15 minutes to accomplish this.

If it won't manually regen, you'll have to get an actual diagnosis. There's a million ways that this can go wrong.

Sent from my XT1585 using EO Forums mobile app
 
J

jon chelton

New Recruit
Owner/Operator
Thanks that makes sense for the p2463, that was the day he drove it back when couldn’t get manual regen to work on the side of the road.

Thanks
 
J

jon chelton

New Recruit
Owner/Operator
Just an update, Turns out someone put diesel in the def tank, needed full cleaning and new catalytic converter.
 
J

jon chelton

New Recruit
Owner/Operator
Just a follow up to this, we are still having issues and are very stuck now.

Once it DEF/Diesel contamination issue was figured out, the whole DEF system was dissembled and thoroughly cleaned and a new catalytic converter installed.

After all that work was done, we still get P0420 catalyst efficiency code.

Any idea where to go next?

Thanks
 
greasytshirt

greasytshirt

Moderator
Staff member
Mechanic
So there are two different catalysts on here. The DOC, or diesel oxidation catalyst, and the Scr catalyst. Generally the Scr gets damaged with contaminated DEF. The DOC may have a separate issue, or it can be a software issue (did you check for possible updates?). Or it could be a combination of things or a performance issue.

I'm not sure if these have DOC and DPF sharing the same container like some Hino's, or if there is an After Turbo Catalyst.

Who is working on it, and what kind of diagnostic tools are available?

There's one at the shop I can look at Monday.

Sent from my XT1585 using EO Forums mobile app
 
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