Joe C5 C2

I had my three year trans maintenance completed last week on my '21 (flush/filter and new fluid) and car ran great coming home from dealer. Busy week so car sat in garage all week until yesterday when I wanted to take it for some errands. Started up and would not go into reverse. Hit the R button and it blinked a few times and went back into P. It would engage forward and move but everything I tried would not get it into reverse. It thru a CEL and the screen said "Service Transmission" and "Idle Creep Temporarily Disengaged". I tried a number of things including the door reboot and nothing worked. Pulled the code which is P0700 (General to trigger CEL), and P073E, "Failure to Engage Reverse". Did an internet search and found that there were a number of posts with the same issue but only one that had a followup with a dealer repair that worked which was a valve body replacement (one guy said he just decided to sell his car to Carvana ). Several did say to let it sit overnight which I did and yes when I tried this AM it went into reverse gear ( CEL still on) so I decided to take it for a short run and it almost passed that test with one exception. Close to home I was going about 65 MPH in auto mode with the trans in 8th gear and then slowed to about 50MPH and gave it some throttle and it would not downshift (pushed to floor and nothing), pulled the left paddle and it went down like it should. Tried this again and could not get it to repeat. I will be calling the closest major dealer on Monday which is Hendrick's flagship store City Chev. figuring they have seen quite a few for warranty work and given their connection may be able to get parts within a reasonable time. Collective thoughts would be appreciated before I go to dealer on Monday. I promise to update on what solves this issue. Thanks guys!

jagtoes

Take it back to the dealer who did the transmission service.

Ron_Attleboro_MA

Weird Joe. Could it be the 'flush' procedure freed up something and caused the problem?
Could another 'flush' clear out any debri and fix the problem? Would this be worth a try by the dealership?
Best wishes. Hopefully nothing worst than a valve-body and especially no transmission replacement.

Joe C5 C2

It could be as you say something was dislodged and another flush would help. What I didn't mention above is after I scheduled the service the car thru a similar CEL and the sub-code mentioned some form of debri. I was hopefull the flush performed would take care of that situation.The dealer cleared the code and did the service. There was also an outstanding recall notice on the '21 models for the trans that flashed the computer to help with communication which the dealer performed when servicing so it could be several things which we will see if they can correct. Thanks for your post.

sowega

Sounds very similar to an issue with mine. They replaced the valve body (after waiting five weeks for the part to arrive), and it appears to have sorted out the issue

Joe C5 C2

That's what I am guessing. Glad they finally got your situation worked out with the replacement.

Joe C5 C2

Update: Took the car out late this afternoon and it is operating perfect. When went leave I still had my scan tool hooked up and it thru the sub code from before service which is P0286. So I come out of the store to go home and NO CEL anymore. Got home and the only codes were the original two. Got to love these computers on wheels.

sowega

fingers crossed that it’s just a ghost in the code. On mine, it threw a code, disappeared for a year, and then started getting rough shifts, limited gear usage, and idle creep disabled, etc

dohabandit

I had a CEL on mine in the first 2k miles. It was a P code related the DCT and a sensor/voltage out of range (too high).
I did a DCT filter change at 1500 miles, and it cleared on it's own without any other service work done, and no issues since.

Vetteman Jack

Moving this to C8 Tech for further discussion.

Joe C5 C2

I followed your thread and didn't remember you had that lag time. My car has had the shift control on the console replaced about two years ago so maybe I am facing what you just mentioned, ghost codes . I am still going to talk to the dealer and see if they want to take a look. Fortunately the two codes are still stored even though the CEL has extinguished itself so the dealer can see those. The dealer will still have proof of the CEL because the P0700 code is generic for triggering a CEL. I wish the third code was still there because it referenced the "Pump B" having a problem. I still have four years on the power train warranty due to it being a CPO car so I have time to see if things come back. I just don't like the possibility of not being able to get reverse in the future.

Joe C5 C2

Glad that worked out for you and hoping for the same outcome. My recent filter change was the second for the car being the first one was the free one.

Joe C5 C2

Glad that worked out for you and hoping for the same outcome. My recent filter change was the second for the car being the first one was the free one.

Post #409, such a good number from the past.

Bob Paris

How many miles on your car?

Joe C5 C2

Miles are at 17,250.

Bob Paris

Curious why you replaced the DCT filter at the 3-year mark. The DCT fluid change is required to be changed at 45,000 miles or 3 years, whichever comes first, but this does not require a DCT filter swap. Assuming your first DCT filter change was between 7,000-8,000 miles, the next filter change would be due at 22,000-23,000 miles. To maintain warranty, will you have to change the filter again in 5,000 miles?

Red Mist Rulz

There's no stated requirement from GM that the 2nd filter change has to be within +/- 500 miles of 22,500. That interval is only spec'd for the first filter change when, presumably, you're getting critical break-in wear particles (and if you believe the internet, left over manufacturing debris) removed from the fluid.

Bob Paris

I never said there was a stated requirement for the 2nd filter change to be +/- 500 miles of 22,500.. The requirement was that the second DCT filter change be 15,000 miles AFTER the first. And if the owner did the first change at the prescrribed mileage of 7,000 to 8,000 miles, then adding 15,000 miles to that specific range example, would require a DCT filter change at the sum of adding 15,000 to the mileage when the first filter was replaced, which will be between 22,000 and 23,000 miles. As an example, if the owner changed the filter at 7,400 miles then the next change would be due at 22,400 miles. It is fair to assume that one could be over by 500 miles when that second service is done and not have to worry about it affecting the warranty status. At least, I would not worry about it. I am curious if the OP will be getting the DCT filter replaced for the third time at 15,000 miles past the second service' mileage.

Avanti

The thing is, ever since the C5s (at least) there can be rare electronic flukes. Many of us have seen some sort appear once or twice and never again... or very infrequently. I once had a dealer see a code flash up and disappear, not set, and never seen again. So, let's hope...

Joe C5 C2

Simple answer why I replaced the filter was because why drop everything for the fluid change and then come back and do it again in a few miles for filter. I won't be anywhere near 45,000 in three years so I will do the filter again early when it is next due for fluid change in three years. It is easy and simple to remember that every three years I do the entire job and not worry about it. Given the number of grit problems I have no issue doing the filter more often to play safe. And besides the cost to do the entire job was $790. out the door for everything (my engine oil/filter was on GM CPO).