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-   Duramax Fifth Generation: 2011-2016 (LML) (https://www.dieselplace.com/forum/63-gm-diesel-engines/365-duramax-fifth-generation-2011-2016-lml/)
-   -   Error code P21DD (https://www.dieselplace.com/forum/63-gm-diesel-engines/365-duramax-fifth-generation-2011-2016-lml/716402-error-code-p21dd.html)

sfrandrup4434 03-05-2015 05:34 PM

Error code P21DD
I have a 2013 Duramax that of course has the stupid DEF, my check engine light came on Monday and Orielly's said the code it was giving was P21DD but there was no explanation...does anyone know what this means?

btexpress 03-05-2015 05:58 PM


Page 304 of group 13OBDG09

sfrandrup4434 03-05-2015 06:20 PM

Thank you! Do you know how to go about fixing it?

sfrandrup4434 03-05-2015 06:22 PM

Do you know if it's due to weather? I live in AZ it doesn't get TOO cold here but I WAS playing in puddles on Sunday and I thought it could be from that...

btexpress 03-05-2015 06:23 PM

No, mine has not misbehaved yet, 25,000 miles, I have a TechII and the GM SI information, just waiting until the day.
You might get under it and unplug, clean & put die-electric grease on them, Then reconnect, since you went through he water.
Did you read the description?

sfrandrup4434 03-05-2015 06:33 PM

I have 46000 on mine, my husband is going to love me for this one :) I sent him the information on it. It couldn't have been an easy code like replacing a gas cap. Thank you so much for the information!

rob1 03-06-2015 10:07 PM

It's likely that the heater that the code pertains to is faulty - at the dealer we would use the scan tool to monitor the amperage drawn by the heater in question and compare it specs. Can't open SI on my phone or I'd say what that is.

I wouldn't just replace the part without actually testing though.

Ramblinrodney 03-06-2015 11:01 PM

Found this.
2013 gmc, 16,370 miles, cel on with P21dd code and is currently at dealership for def heater element replacement. Vehicle has been there since April 1st and waiting for part to show up the week of the 14th from gm. So my vehicle will be there over two weeks and not very happy.

Is it under warrenty yet?

Moneypitt 04-22-2015 08:50 PM

Just had this code show up today on my 2013 with 31,300 miles on it.

eric2063 04-22-2015 11:46 PM

Mine went south Sunday, it's sitting in Kellogg waiting for the part to get here from Reno. Maybe fixed by Friday, I'm getting prices for a full delete. It's been in the shop 3 weeks already since January for DPF/Emissions issues :mad:

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