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eggtrucks · 06-12-2021, **(Subject: spn 1231 )**

Need help with a Paccar px-8, is throwing code spn 1231 and while driving turbo often chuffs/sneezes when under a load. I replaced turbo because selector gear was stuck and wouldnt pass the vgt acuator test, and thought this was causing the sneezing. With new turbo it has the same problem. No check engine light, but its giving code spn 1231... any advice?? 2012 Pete 348, 150,000 miles, all local. i got DPF, DOC baked/cleaned, replaced egr valve

hookliftpete · 06-12-2021, **(Subject: spn 1231 )**

Exhaust pressure sensor cleared up similar symptom on my px8/isc.

Rawze · 06-12-2021, **(Subject: spn 1231 )**

do a full egr tune-u-p on it... clean out all the piping, replace intake and egr sensors, etc.. and you might have to clean out the egr cooler too if it has more than 600k miles on it.

If its anything like a red engine, they chuff like that because the thing cannot get enough egr gas flow thru the egr circuits... and it drives the turbo to high positions to overcome the restrictions.

eggtrucks · 06-15-2021, **(Subject: spn 1231 )**

(06-12-2021 )Rawze Wrote: do a full egr tune-u-p on it... clean out all the piping, replace intake and egr sensors, etc.. and you might have to clean out the egr cooler too if it has more than 600k miles on it.

If its anything like a red engine, they chuff like that because the thing cannot get enough egr gas flow thru the egr circuits... and it drives the turbo to high positions to overcome the restrictions.

Thanks! The port was packed with soot to the egr delta pressure sensor, runs like brand new now!