Auto Start/Stop check-engine light 5X failures

Jack Pouchet · December 3, 2020

The back story on my 2020 Chevrolet Silverado 1500 LT Trailboss.

Love the truck - not the check engine light. This week is my fifth time taking the truck in for a faulty auto start/stop system.

Purchased new July 19, 2020.

VIN# 3GCPYFED7LG351512

GM Customer Case number: 9-6360533449.

Current odometer 2,269, at least when I dropped it off for service on Monday morning. The last repair attempt saw the dealer drive the truck 38 miles. And they still weren’t able to make an effective repair. Next time let me do the test driving.

All previous repairs have been useless. Within a few days to a few weeks of service the truck exhibits the same issue.

Runs fine, auto start/stop is ok then all of a sudden during one of the re-starts it seems to hesitate. Not much but enough to make the truck feel ‘weird’ like it is sluggish starting and coming up to speed. Check Engine light turns on.

I immediately get two emails from OnStar Diagnostics. One stating a problem with the engine / transmission and the other stating a problem exists with the lithium battery. Now this is one part of integrated electronics and communications that makes sense. I do like having this information with the convenient time stamp. Especially as if I keep driving the vehicle a few days, or leave it parked, by the time I drive it to my local dealer the check engine light has turned off.

I would be delighted to talk to any of the GM engine / electronics engineers that want to learn more about the issues I am having. More than happy to have the truck loaded with additional real-time data recording to isolate the root cause of the problem. My guess is a combination of faulty sensor and a buggy / defective control module.

I have now written two letters to GM advising them I am not happy with the truck. That this is now repair attempt number five and I have no confidence in their ability to execute a complete, long-lasting repair.

As of today, Thursday December 3 the truck has been in for service going on day number four and the best service technicians in SoCal and Detroit are coming up clueless in diagnosing the root cause of the problem.

Makes me want to go back to an old F150 4x4 Crew Cab with manual transmission, manual hubs, a real distributor, carburetor, seat belts, etc. Give me something reliable that I can work on and repair myself.