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Old 10-15-2017, 12:19 AM   #1 (permalink)
Sparkplug Hunter
Join Date: Oct 2017
Posts: 1
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DEF Trouble Codes - And Final Countdown

Started out with Code P21DD, which came on as a permanent code that I couldn't erase coupled with one that I could erase. Seems like it only. Each time I erased it, the service engine light turned off (even though the permanent code remained).

Unfortunately, last Thursday I was driving to work and the service exhaust system light on the dash appeared along with a countdown to limited speed. Checked the code and got P20B9, Reductant Heater A Control Circuit/Open.

Not wanting to go full limp, I replaced the heater today. Wasn't a difficult job. Only took a few hours thanks to YouTube University.

All of the erasable codes were cleared prior to my test drive. I was happy to see that the service engine light stayed off during the drive and I was hoping the truck would go through a regen and clear the permanent codes and stop the countdown.

Wellllll, after a 30 mile freeway drive and 10 minute idle in the driveway, the service engine light came back on and the countdown to reduced speed continued with the service exhaust system light still lit. Checked the codes and saw that the original errors had cleared, but now I have a new one...P20E9, Reductant Pressure Too High.

I NEED the truck for work on Monday. I'm wondering if I allowed some grit to get in the DEF injector hose and plugged the injector line? I'm going to remove the entire system again in the morning and see if there is anything obvious.

Does anyone know of a quicker way to clear the permanent codes without computer software? Or is there a code reader out there that I can purchase on a Sunday that is known to do it? My code reader is a BOSCH from O'Reilly, but it will not clear the permanent codes and I need to somehow stop the countdown (I have 19 miles left before being limited to 55MPH and 65MPH is slow enough!)

2014 GMC Sierra 2500HD Duramax
128,000 Miles
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Old 10-15-2017, 08:31 AM   #2 (permalink)
Diesel Ace
Join Date: Mar 2005
Location: chi-town
Posts: 12,722
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there is a TSB[tech serv bul] for pluged Reductant line/inj plugged

you need a ''gm tech2'' scanner and run a ''forced regen'' and a test of Reductant inj system

2013 2500 ltz 4x4 d/a,, fully loaded ,white crew cab
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