LML Chk Engine P21dd code

[chris199]

Manual says Reductant Heater #1 low current.

Is this something I can fix or replace?

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[chevyburnout1]

More than likely the heater in the DEF tank needs replaced.

 

[chris199]

Any downside to clearing and seeing if it recurs?

Will be warm a few days...probably won't recur until it's cold again?


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[chevyburnout1]

I'm pretty sure it'll reappear within a few ignition cycles. The ECM monitors the circuit status regardless if it's in use or not. It's like having a bunch of little multimeters hooked up to each circuit. The resistance is more than likely outside the set factory window.

 

[Big Block 88]

It will reapear im fighting it right now with our lml. Dealer wants $800 to replace the heater in the tank.

 

[chris199]

Yeah..it came back on. Dealer had a hard time finding the heater. They ordered it... $275 for the heater only...no tank, no resevoir, no labor. Will know actual cost next week. Left truck at dealer for the week.

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[chris199]

Conclusion: Took 10 days for dealer to get the new resevoir.

Great news: Repair done at no charge for parts and labor. Covered under emissions warranty....Surprised by that...over 75,000 miles on it already.

Very happy with GMC....part availability issue notwithstanding.

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