Some 2020 Corvette Owners Are Getting a Check Engine Light, But No Noticeable Performance Issues


Some 2020 Corvette Owners Are Getting a Check Engine Light But No Noticeable Performance Issues

Within the last week, we’ve been contacted by no less than three different 2020 Corvette owners about an issue they have with their sports cars, and now GM has a TechLink article up about it.

The owners are reporting that a “Check Engine Light” comes on along with a message that power may be temporarily reduced, yet we were told they felt no issues with power.

Here’s one of the emails that I received last week:

I took delivery of a 2020 Corvette coupe on September 03. About 2 weeks later the ‘check engine’ light came on. I took it to the dealership. When I picked it up they had managed to get the engine light to go out, but they told me it was a temporary fix and that GM was aware of the problem and was working on a permanent fix.

I drove the car about 2 weeks and the ‘check engine’ light came back on. I took it back to the dealer on October 16, and it is still there. They again say they are awaiting a fix, I assume of a computer or software type.

The day after I received this email, I was made aware of a new GM TechLink article, and believing that this was the issue with the owner, I sent it over to him.

A second owner with this same issue called me yesterday about it as well. He was noticeably upset about the issue and told me he just might sell the car and be done as he was scared to drive it. He described the same issue, which is a Check Engine Light coming on, and specifically told me that his service techs mentioned the Transmission Control Module (TCM) which is also mentioned in the TechLink article.

GM appears to be working on a software fix for whatever is causing this, but we wanted to make owners aware just in case they are getting similar messages.

Here is the GM TechLink article that was published 10/28/2020:

DTCs Set in the TCM

October 28, 2020

Some 2020 Corvettes may have an illuminated Check Engine MIL and a reduced engine power message on the instrument cluster with no noticeable performance issues. DTCs P1967 (Serial Data Message Safety Performance 1) and/or P1968 (Serial Data Message Safety Performance 2) may be set in the Transmission Control Module (TCM).

Follow the diagnostics for these DTCs in the appropriate Service Information. If there are other DTCs set in the TCM, diagnose those DTCs first.

If only DTCs P1967 or P1968 are set, do not request a TCM replacement (Fig. 21 above) per #PIP5703 (TCM Restriction). Perform the even and odd-related clean procedures in GDS2 and a transmission service fast learn. After completing these procedures, re-evaluate the condition.

These conditions are not a performance issue with the TCM or transmission assembly. A software update is currently being evaluated.

Transmission Control Module

For additional information, refer to #PIP5757.

GM TechLink

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  1. Maybe I should be relieved that I am getting the 2021!! The first year of a lot of new models usually have the problems. Probably nothing to worry about and an easy fix. Not like they just started building cars.

  2. K.G.+1: Although my first year C7 had teething problems(info. screen, gearshift engagement and, skip shift) it was nothing like the drumbeat of issues high and low (valve springs!) tech like these C8’s. I’m glad to keep my C7. Its sexy and (relatively) uncluttered styling, manual 7 speed transmission and perfect 50/50 weight balance ( it won’t fall off a lift) make it a keeper!

  3. Yep, love my C7 more and more. I would like a new C8 but when they are asking 100K on ebay. I will just enjoy my 19 Stingray. No rush anyway.

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