Jump to content

Diagnostic code p21dd

Car54

By Car54
in Troubleshooting & Recalls

 Share

Recommended Posts

Car54 New Member

Car54

Posted
Posted

My check engine light came on so I ran code check which showed DEF reluctant heater failure. I got a letter sometime back from GM stating that this issue was now covered under an extended warranty. My problem is my closest dealership 62 miles, told me they are booked until May 24. I saw on other forums that the truck may go into "limp mode" if I drive it? Has anyone dealt with this issue out there, I have other dealerships 250 miles away just don't want to pay a tow bill trying to get there 

Hillwood Enthusiast

Hillwood

Posted
Posted

If you haven't seen the message on the DIC yet, it might not go into limp mode.. The DIC will state the message when it does.

You might want to post this on the HD section.  This is the LD 1500 section. 

EJCarter Enthusiast

EJCarter

Posted
Posted

I had the same P21DD code come up about three months ago. My dealer ran the check and the DEF heater / pump assembly would need to be replaced...but it was on a nationwide back order. They cleared the code and let me know they would call when the part came in (they had 10 on order as a couple other trucks had the same code and needed the same part, plus they wanted some in stock). Approx a month later, they received a few heater / pump assemblies and replaced mine.

During that month wait, my check engine light did come back on a few times. I asked the dealer about the truck going into limp mode. They said there is a chance, but it should be a rare occasion from this issue. I wasn't too confident in their answer. They also stated, like Hillwood stated above, it will come up on the DIC and give you a number of miles before going limp...I think they said like a 50 mile "warning."

The dealer also knows I have a CTS2 monitor that will run and clear codes. They said to clear it if it returns. This will keep from driving it too long with an active code (CEL), thus reducing the chance of it going into limp mode. I never had any limp issues, limp warnings, etc...and my CEL was off when I took it in for replacement. Since it's been replaced, no further CELs have come up... 

 

I would confirm your closest dealer has the part in stock. If so, see if they can put one aside for you so you don't waste a trip. If they don't have any in stock, see if they can order some now... 

It should only take about an hour or two to replace if they have a good diesel mechanic.

I wouldn't worry too much about the limp mode. It sounds like you were able to read your code ?  If that's the only code you are seeing, I'd clear it. If it comes up again, confirm it's the same P21DD and clear it again...

And yes, this part is covered under warranty. GM is having so many problems with our DEF / emission system, they extended the warranty on it. I believe I heard it was 10 years /125K miles...but double check that... 

markwadeewen Enthusiast

markwadeewen

Posted
Posted

Mine gave me the same code yesterday. I took it into the dealer today & they put it on there scanner to confirm code. Now I am getting a message saying that I have 160 km till the 105km/hr max speed. Took it back to the dealer & was told that they cannot clear the code cause the truck needs to go into regen mode to clear & they cannot do a force regen because they need tank heater for it to happen. So now I got 160 km till Speed is reduced & they figured another 200 km at reduced speed then truck will only idle. No def tanks around so it will be over 3 weeks before they get one.
Anyone else ever have this happen? Seems weird to me that GM never thought this through & had a fix in this kind of situation.


Sent from my iPhone using Tapatalk

Car54 New Member

Car54

Posted
  • Author
Posted

Eric thanxs for the info. I will definitely call the dealership and see if they will order the heater now. 

Car54 New Member

Car54

Posted
  • Author
Posted

Just some quick follow up on the P21 DD code. Dealership took care of it under warranty and they had the heater in stock!  Drove my truck approx. 100 miles prior to the repair and I never got a DIC message relating to limp mode.  

  • 1 year later...
Erodz New Member

Erodz

Posted
Posted

I have a 2014 2500hd, I had the codes P21DD and P20B9 with a “service exhaust fluid system” warning. I replaced the heater pump my self and cleared the codes with my scanner. Ran the truck for a little while, codes haven’t come back, but the “service fluid system” light won’t go away. Any thoughts? 

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Recently Browsing   0 members

    • No registered users viewing this page.

  • Forum Statistics

    250.5k
    Total Topics
    2.7m
    Total Posts

  • Member Statistics

    342,889
    Total Members
    8,960
    Most Online
    smandy
    Newest Member
    smandy
    Joined

  • Who's Online   4 Members, 0 Anonymous, 500 Guests (See full list)

  • Latest Articles

  • Posts

    • Coastie05
      2027 GMC Sierra: Official Discussion

      By Coastie05 · Posted

      Sure, but they do have some affordable options like the Trax, Trailblazer, Envista, and Encore. Some of these have a cheaper base price than the Civic, though the fuel economy isn’t as high. The main problem is that people WANT the highest trim with all the goodies and finance for like 7 years. That’s how ppl “afford” the more expensive vehicles. 
    • Jsdirt
      07 yukon xl 6.2 stalls at hot idle and wont restart

      By Jsdirt · Posted

      Holy s**t - not much of a parts thrower you say? You BLASTED that thing with the parts cannon!  You'd have been probably $1,000 ahead if you had just brought it to a competent shop rather than shotgunning a bunch of parts it clearly didn't need.   Just FYI - oil additives are really, REALLY good at ONE thing ... and that's emptying your wallet. They're ALL useless gimmicks.   If that has the L94 or L99, then #7 is an AFM cylinder. I'd suspect a failed lifter in that case.   If you leaned on wiring, sensors, and/or connectors while changing the oil, you'll have to check all that to be sure pins didn't get pulled out, connectors broken, etc.. Old wire loom that was barely adequate when new is certainly brittle by year 19 - make sure wires aren't chaffed and shorting out somewhere where you might have leaned. or supported yourself on it.   If your a mechanic, why didn't you just find out what you were missing and troubleshoot from there??  TIMED spark, fuel PSI / injector pulse, air, compression.  Can't make ANY money going the parts cannon route.
    • Jsdirt
      2027 GMC Sierra: Official Discussion

      By Jsdirt · Posted

      LOL! Are you joking?? That wax SUCKS! 100% gimmick made to "look" good.    After just TWO winters I had severe surface rusting in patches over 90% of the frame. Only reason it looks great in the pics is because I SATURATED the frame every single fall with used motor oil for 14 of the 16 years I owned it. Otherwise it would've been sent to the crusher 8 years earlier with the speed it was rusting prior!    I sold that POS 3 years ago. Was a gigantic headache the second it rolled off the showroom floor. Brakes pulsated on the TEST DRIVE. Door trim fell off the 1st week! Interior squeaked and rattled, and the drivetrain clunked after 2k miles. 4x4 switch failed shortly after. Front end - ball joints, struts, hub bearings - all failed between 38k-50k. Engine started burning oil at 50k. Rear and and transmission failed before 100k. Nothing but problems, and frustration with the piss-poor engineering designed to make you give up. Well, it worked! Nothing on that truck was easy to remove ... except the wheels. They haven't figured out how to screw that up yet. Give 'em time ...   I won't make that mistake again. EVER.   Such fond memories ... https://postimg.cc/K1qf23tS  https://postimg.cc/gallery/X02z64J  https://postimg.cc/gallery/mHSRXZv  https://postimg.cc/gallery/D4mMRfL
    • davester
      OBD not ready?

      By davester · Posted

      Different monitors do their test only under conditions specific to that monitor.  you MIGHT find the drive cycle conditions for the monitor that isn't ready on this site: https://lemon-manuals.la/   If it's not there, then it should be on alldata.com for your truck, but it requires a paid subscription.   And you need to know which specific monitor isn't ready.
    • RW2018GMC
      Me too……..

      By RW2018GMC · Posted

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...