Is your defective GMC Denali actually a LEMON?

Find out in 30 SECONDS or less if it qualifies for a REFUND or a CASH SETTLEMENT.

4.0

definitely annoying
Typical Repair Cost:
$170
Average Mileage:
122,000 miles
Total Complaints:
1 complaints

Most Common Solutions:

  1. sensor replaced & codes cleared (1 reports)
Get free help with your lemon!
close ad
2021 GMC Denali exhaust system problems

exhaust system problem

Find something helpful? Spread the word.
Get notified about new defects, investigations, recalls & lawsuits for the 2021 GMC Denali:

Unsubscribe any time. We don't sell/share your email.

2021 GMC Denali Owner Comments

problem #1

Dec 282024

Denali 2.8L

  • Automatic transmission
  • 122,000 miles

A D V E R T I S E M E N T S

click to see larger images

service engine light code #p1478

Service engine light came on a few weeks ago. Had a diagnostic ran & it came up P1478 "Particulate Matter Sensor Temperature Circuit High Voltage". Did my research & it seems one of two problems may have occurred.

  1. Wire harness has burned through by contacting the exhaust pipe.
  2. The sensor has went bad.

    Either way, I figured the sensor would need to be replaced. With my truck being a 2021, parts haven't made it to third party places like Auto Zone & O'Reilly's. Called the dealership & they wanted $184 for the AC Delco part. Went to the AC Delco store on Amazon & bought it for $83 & free Prime shipping. The part arrived & I am having my mechanic install it on 1/24/25. I will report back if the problem is fixed.

    On a side note, it does not appear this issue has caused any problems with MPG or performance.

    Update from Feb 7, 2025: I purchased the new sensor from the AC Delco store on Amazon. I had my local mechanic install the new sensor & clear the code. It's been about two weeks now & the new sensor seems to have fixed the issue. My remote start is working again after the part replacement & codes cleared

- Trace D., Scottsburg, IN, US

Not what you are looking for?