Forum Discussion

HuckleberryHunt's avatar
May 23, 2019

Chevy DEF system failure

Just sharing for other's reference.

I own a 2016 2500HD diesel. It currently has 40k miles on the OD. Two days ago the check engine light came on. I checked the error code and it came back as a DEF system error (P21DD). I took it to the dealer on Wed morning to have it checked out. It took all day for them to get back to me, but the guy said that it's the DEF tank heater failed and it's a common issue. The parts are on backorder and it could take a month to get them in, so to drive it as is until then. He did say it might go into 'limp' mode at some point. I asked why it takes so long to get parts if these systems are a common issue. He didn't know.

The good news is that the repair is covered under some type of warranty....either emissions or drive train...or both. The guy also wasn't quite sure how that all fit together either. I asked about longevity of the repair and he said it would be covered under a parts warranty for a period of time....which I'm sure is less than 40k miles. It does make me leery of future failures though, but I bought the truck knowing the DEF was likely a PIA, so guess I'll deal with it as it comes.

He did say that GM will be removing the DEF systems on future vehicles because of all the problems they create. I would like to know where he got his information as I've not been able to find any evidence that supports that happening via a web search.
  • It is a good idea to get a good scan tool that can read the error code and clear the CEL, I have a Edge insight on mine and it works great. I can monitor soot level and even force a regen, mine will automatically regen when it hits 43 grams of soot. If the soot level is getting high and I know I will be driving long enough to burn it out I will start a manual regen.
  • and these and other problems with add on epa stuff is why I drive a gaser. used to love the old 7.3
  • My 2013 had the same issue, I drove it for two months until the new DEF tank arrived. The truck never went into limp mode.
  • 2011 chevy 2500 hd at 49000 def fluid bad came on took to dealer was under g m extended warranty for 11 & 12s , or about 1.5 years left , same thing bad tank heater & 1 nox sensor replaced asked how much would it cost if not under warranty , $1,000 ..
  • That's the reason I bought a gasser 2500 last time I bought new. That was 2014, and the DEF & DPF systems still had bugs. The emissions junk the new diesels are saddled with are ruining the reliability and making the prospect of any repair a potentially expensive process.