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'20 CT4 w/P04FB code

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21 - 40 of 41 Posts
#21 ·
I'll join the club 2021 ct5 i have been to dealer 4 times now. This last time they said part was in. I picked it up and they told me check engine light wasn't on. Liars, it's been on for weeks. They told me manufacturer was working on a solution and will call me when they are ready. Just got home from dealer, I'm sure light will be on tomorrow. They don't realize I was a Mechanic for 33 years. And if they knew they weren't going to replace sensor then why did I drive out to them. Pretty upset.
 
#23 ·
SystemsGuy said:
My wife has a 22 CT4 AWD Prem Lux with the 2.0 LSY in it - first owner. We had this happen a couple weeks ago and when the weather warmed up it went an away. It just came back again on Thursday or Friday. Both times her car was running real rough. I thought code would go away again but no luck. I’m in Michigan and know of the Novi dealer well. Also found the TSB on this issue.

It was way too cold here to remove the pressure sensor this weekend. I got the bright idea to use a heat gun on it. Did some research and talked to father-in-law who is a GM Engine Engineer prior to doing. I set the heat gun to 250. It was 1 degree out last night!!! Ran it about 5m pointed at sensor from an inch away, then started car. Ran heat gun for another 10m. Then cleared code. Was able to remote start. Took the car to get gas and then ran it up i75 to sashabaw road. Parked. Pulled codes again. Still in perm register, but suspect a little more driving it will clear. Started back up and drove home. Car performed great. No more roughness.

Remote started again today. Will see what we’re looking at when wife gets home.

All I can think of is we’ve had some bizarre days here in Michigan with high humidity and huge temperature drops at night. Wife has a short 6 mile ride for work. Engine never really gets hot enough long enough to evaporate any moisture off???

I use the Blue Driver OBD tool. Bought off Amazon couple years ago and sync to phone.

Will let everyone know if it stays off. Otherwise I’ll pull it and run heat gun to see if any moisture comes out.

2025-02-19 update. Multiple remote starts. 75mi driven since heat gun used on sensor and codes cleared. Pulled codes again tonight and the permanent code is gone. Vehicle feels the problem is resolved. It’s still cold as all get here was 5deg this morning and only 10deg right now.

Added photo for anyone that wants to try.
View attachment 674709
Click to expand...
Could you take another photo? This is washed out on my screen. Also, a zoomed out photo showing the engine bay location would be helpful.
 
#24 ·
Sorry flash went off and lighting not real good on that area of driveway. I’ll pop out there during daylight here shortly and get an overview of the bay and a better zoom in view for you today.

it should be warmer today. So I’ll also fiddle with sensor to see if it seems seated well. Didn’t want to break it when it was only 1deg out. I had an issue couple years back on XT4 where check engine light kept coming on. Mass airflow sensor was not seated well, so was sucking in debris. Doesn’t seem to be case in this situation as multiple people had dealer remove and reinstall. I am wondering if during cold the plastic is shrinking too much and the o-ring isn’t big enough to account for shrinkage??? Now that I may have a no removal fix, I want to figure out root cause.
 
#25 ·
Got home too late yesterday. Got some photos for you and mocked them up. So I heated the "intake pressure and temperature sensor" using Wagner Furno 750 set to 250deg. I DO NOT believe this to be the correct solution. I should have heated the "Crankcase Pressure Sensor".

I started the car after 5m, then heated for 10m more. It was 1deg out last Sunday. I then cleared the codes. Turned car off and successfully tested remote start. I then took the car on a 32mi round trip. So, I think the long drive thawed out anything frozen and got rid of moisture. Clearing codes got the engine running smooth and allowed remote start.

What really has me puzzled is the car was NOT running rough when I first started it, which would seem to indicate intake sensor heating helped. But it is NOT the sensor that dealers and bulletin call out.

Four weeks ago was the first time the car threw the code in three years. If it happens again, I intend to heat the "intake pressure and temperature sensor" for 5m and start the car and see if it runs rough. The whole time the check engine light was on the wife complained about how rough it was running.

This is my OBD scanner: BlueDriver Bluetooth Pro OBDII Scan Tool for iPhone & Android -
https://www.amazon.com/dp/B00652G4TS I used drive with it in my XT4 all the time, and keep it in my XT6.

Hope this helps. Would also like to hear of any success anyone has.


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#26 · (Edited)
So is the whole big deal that the remote start doesn’t work properly in very cold weather? I agree that no one wants to sit in a cold car while it warms up, and if you have the feature it should work, but it’s not like you’re getting stranded either. What are the CT4 owners in North Dakota doing?
 
#27 ·
hammerin16ds said:
I have a 2024 silverado with the same issue and they won't do anything to fix it or relove the issue. Just say sorry the parts on back order so you will just have to deal with it. Complete nonsense $50,000 truck in Michigan with no automatic start! So what are my options?

@hammerin16ds- profanity is not permitted and has been removed from your post.
Please refer to the terms you agreed to when joining Cadillac Forums.
-Long
Click to expand...
Move to Las Vegas.
 
#28 ·
21drfrank said:
So is the whole big deal that the remote start doesn’t work properly in very cold weather? I agree that no one wants to sit in a cold car while it warms up, and if you have the feature it should work, but it’s not like you’re getting stranded either. What are the CT4 owners in North Dakota doing?
Click to expand...
If it was just remote start it would be just an inconvenience. However, ours runs awful when the light is on. Idles rough. Acceleration terrible. Overall performance horrendous. And when it’s running like this you do wonder is it going to just not start and strand you at some point.
 
#31 ·
klahache19 said:
Hey engine light just came on yesterday, which is a pain because I need remote start for the cold mornings. P04FB code.
I still have the "new cadillac protection plan" warranty, Just wondering if that would be 'excluded' for some reason.
Anyone else have this issue?? 2020 CT4 2.0T here
Click to expand...
Same problem here, what good does the remote start do us if this engine light keeps coming on when its cold!
 
#37 ·
Cadillac ryder said:
I just got the same code,P04FB. Cleared once then came back maybe 12 hrs later during a remote start attempt. Does in fact prevent remote start it seems. Its under factory warranty i believe, so im gonna call the local dealer.

Looks like it may have triggered a few other codes, cause scanner shows failed then successful; U04220, U0447, U0131, U1616, U1611.

It has been rather code lately, 20F and below.

2023 CT4 2.0 RWD
32200 miles
Click to expand...
I keep taking mine to dealer and they refuse to change the sensor! Haven't had my remote start for two winters now! 2022 CT4 Cadillac.
 
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