[Shtaka]

I bought my 2019 this past September. I did not purchase from a Caddy dealer, but the car is still under warranty. After getting to know the car for about two weeks I brought it to the local Caddy dealer for a couple of minor warranty issues. They had to order a part and I made an appointment to come back the next afternoon. I stopped for a haircut on the way home. When I started the car, I had a Check Engine light. When I brought it in the next day, they told me to leave it. I was without the car for a week. The problem was issues with the Camshaft Position Actuator and Caddy not putting timing marks on the engine.

When I got it back, I used the car maybe once or twice and then it sat for a week while I was away on a trip. When I got back, I was running errands and floored the throttle coming out of a parking lot. Out of the corner of my eye I could see the tach redline and then fall. There was no power. I wasn't really sure what happened and fiddled with the shifter thinking it had something to do with the transmission. I don't know exactly what I did, but the car returned to normal.

So, of course, I tried flooring it again and the same thing happened. Fiddled with the shifter and it returned to normal. I thought about it a bit and realized if I was going to bring it in, I needed to be able to replicate the problem on demand. And, of course, I couldn't after trying a couple of times.

Out the next day and my wife is driving. "What's this little red light?" Check engine.

I bring it back to the dealer. They cleared "old" codes and drive the car for a while to see if new ones were generated. They weren't, and I have the car back now after another couple of days without it. So far, so good but I am nervous the light will come on again. It's going to take a while for me to have full confidence in the car again.

Any insight into what might be happening or how to diagnosis it?

 

[Submariner409]

The car has its own built-in diagnostic code scanner (OBD-II - OnBoard Diagnostics-II protocol)). Have it read and printed out at a parts store, use the below link to decipher the found codes and post it all here. One or more members who are owners of the same vehicle/powertrain will chime in.

OBDII diagnostics. Trouble codes description for GM

OBDII/EOBD diagnostic code definition. More than 18000 codes for all autos. Trouble codes description for GM

obdii.pro

Codes read out as a letter, 4 digits, maybe a suffix letter.

P = Powertrain
B = Body
C = Chassis
U = power and data

XXXX

C = Current (the problem exists now)
H = History (the problem was detected 3 or more start-run-drive cycles ago but has not been detected recently)

Once things are fixed and/or the code goes to History it remains there for X or XX start-run-drive cycles during which the fault is not detected and then self-clears from the memory. A good plug-in scan tool or a GM Tech-II can clear codes, too.

 

[Team ZR-1]

During the servicing, may have caused a DTC to trip and tech guy did not clear them when done
After clearing them then drive a few days and see if no DTCs trip

If CEL returns, you need to report what DTC(s) tripped

 

[Shtaka]

During the servicing, may have caused a DTC to trip and tech guy did not clear them when done
After clearing them then drive a few days and see if no DTCs trip

If CEL returns, you need to report what DTC(s) tripped

DTC?

 

[Team ZR-1]

DTC - Diagnostics Trouble Codes (error codes)

 

[warrenyares]

I bought my 2019 this past September. I did not purchase from a Caddy dealer, but the car is still under warranty. After getting to know the car for about two weeks I brought it to the local Caddy dealer for a couple of minor warranty issues. They had to order a part and I made an appointment to come back the next afternoon. I stopped for a haircut on the way home. When I started the car, I had a Check Engine light. When I brought it in the next day, they told me to leave it. I was without the car for a week. The problem was issues with the Camshaft Position Actuator and Caddy not putting timing marks on the engine.

When I got it back, I used the car maybe once or twice and then it sat for a week while I was away on a trip. When I got back, I was running errands and floored the throttle coming out of a parking lot. Out of the corner of my eye I could see the tach redline and then fall. There was no power. I wasn't really sure what happened and fiddled with the shifter thinking it had something to do with the transmission. I don't know exactly what I did, but the car returned to normal.

So, of course, I tried flooring it again and the same thing happened. Fiddled with the shifter and it returned to normal. I thought about it a bit and realized if I was going to bring it in, I needed to be able to replicate the problem on demand. And, of course, I couldn't after trying a couple of times.

Out the next day and my wife is driving. "What's this little red light?" Check engine.

I bring it back to the dealer. They cleared "old" codes and drive the car for a while to see if new ones were generated. They weren't, and I have the car back now after another couple of days without it. So far, so good but I am nervous the light will come on again. It's going to take a while for me to have full confidence in the car again.

Any insight into what might be happening or how to diagnosis it?

If you saw it red line you hit the rev limiter and it will shut down.

 

[Shtaka]

If you saw it red line you hit the rev limiter and it will shut down.

How does the rev limiter work? Why doesn't it kick in every time I floor it?

 

[resdoggie]

Not sure on the XT4 but rev limiters can work by reducing ignition spark and/or limiting fuel flow to prevent the engine from over revving i.e. going beyond the redline, which will prevent engine damage. It should kick in every time you go above the redline but not before.

 

[Shtaka]

Not sure on the XT4 but rev limiters can work by reducing ignition spark and/or limiting fuel flow to prevent the engine from over revving i.e. going beyond the redline, which will prevent engine damage. It should kick in every time you go above the redline but not before.

Wouldn't the transmission just shift up a gear to prevent that?

 

[resdoggie]

Yes, it should if everything is functioning properly.

 

[Submariner409]

On most of our cars there's an rpm limiter in N or P set to about 4000 rpm to prevent over-revving an unloaded engine. When in gear or D-1-2-3-whatever the rev limiter is set to the loaded engine upshift redline.

The vehicle speed limiter is set to the rated OEM tire max speed - driver's door sticker.

The limiters drop out fuel injectors.

 

[Shtaka]

Another CEL. This time I got the codes from Onstar:

U0101 The Engine and Transmission System is not performing as expected. An issue has been detected in the Engine Electrical System, including the Charging and Starting System that monitors and controls the engine starting system and 12V battery charging system. If the charge system light stays on, or comes on while driving, there may be a problem with the electrical charging system. Driving while this light is on could drain the battery. If a short distance must be driven with the light on, be sure to turn off all accessories, such as the radio and air conditioner.

and

U0129 The vehicle communication system is not performing as expected. Service within 7 days

I did notice that both CEL's were preceded by my switching the tranny to Touring Mode.

I'll mention that to the dealer when I bring it in this morning.

Any educated guesses on the problem?