Anyone seen P1128 Check Engine Light?

[mwilk012]

Your intake you installed, may be the source of the problem. Which one is it?

fueling calculations may change what parameters are looked at and used at any given time, but an individual data line is specific to the exact sensor and only with aftermarket tunes do you get substituted values.

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[XxsullyxX123]

Your intake you installed, may be the source of the problem. Which one is it?

Holley intech. Multiple guys on here no problems. But that doesn’t mean I didn’t mar the IAT sensor or line up the vacuum lines right. Def possible. Why 1000 miles fine after install and then 1500 miles in between reset is beyond me lol. I am taking out out anyway just to see. I did put stock intake in for a week after the first time the CEL came on and it came back with the stock. Although I hadn’t reset the code at that point, only allowed it to disappear on its own.

 

[mwilk012]

Holley intech. Multiple guys on here no problems. But that doesn’t mean I didn’t mar the IAT sensor or line up the vacuum lines right. Def possible. Why 1000 miles fine after install and then 1500 miles in between reset is beyond me lol.

intermittent faults are the worst.

 

[XxsullyxX123]

intermittent faults are the worst.

Sure are. I had an out of warranty 2015 durango with the 3.6 pentastar and a p0456 for a month I was trying to track it down. Turned out to be the evap hard line cracked on the underside at the quick release. Couldn’t see if with all my checking bc it was under. Once I took it off it was clear as a bell. Smoke test wouldve helped but I’m a finance guy who likes to futz around not a mechanic lol

 

[mwilk012]

Man that is just way too early after startup to be setting that code. 13 seconds is not enough to enter closed loop fuel control.

 

[XxsullyxX123]

Man that is just way too early after startup to be setting that code. 13 seconds is not enough to enter closed loop fuel control.

My thoughts as well. No way the cat has warmed even with the warmer. Both times the code was set was at exactly 13 seconds. Both times ambient air and IAT were out of whack and in the 100s on cold starts. I reset the code and we’ll see. May be worth monitoring live data daily for a while particularly at cold starts to see. Just time consuming lol

 

[58Willys]

Drove home (no CEL) with live monitoring on my JScan and Ambient temp was right on a mid 50's (the actual temp) and the IAT was within +5 to +15 degrees of the ambient the whole ride. Weird that both the Ambient and IAT sensor would BOTH show ridiculously false high temps at the same time on a cold start and both be bad, and then both be working. Also curious if there is a potential PCM feature that doesnt allow a reading on the IAT to be significantly below Ambient, and accepts the ambient value as an IAT in that event. Meaning Ambient sensor showed 111 degrees on a cold start in a 70 degree garage, so IAT was forced to accept that value. In no way was that anywhere near the actual temp at the time the code was thrown. Either that, or as you said the circuit (maybe fuse?) or PCM itself. I'll get to the bottom of it one way or another lol

I think you’re on the right track. Who knows what sort of logic/algorithms are programmed into these things. I not sure if the electrical manual has how to test sensors, or if you can even test them without the dealer software.

 

[Maverick909]

The Powertrain Control Module (PCM) detects a condition where the vehicle has remained in open loop fuel control, from a start-up condition, longer than a calibrated amount of time, when conditions would have otherwise closed loop operation.


Most Likely O2 sensor or the O2 not going into ready mode

 

[XxsullyxX123]

The Powertrain Control Module (PCM) detects a condition where the vehicle has remained in open loop fuel control, from a start-up condition, longer than a calibrated amount of time, when conditions would have otherwise closed loop operation.


Most Likely O2 sensor or the O2 not going into ready mode

I originally thought o2 sensor the first go around, but this code would normally be paired with another code (ie: o2 sensor code that then causes it to not get into closed loop). In any event, as @mwilk012 said earlier, there is no way that would be able to go closed loop regardless at 13 seconds after a cold start up. The only wonky readings (that are obvious to me at least) on the CEL's are the ambient temps and intake temps. If anything, I would say that something was tricking the PCM to THINK it was supposed to be into closed loop already, when in fact it was not supposed to be yet. aka, a bad on a temp sensor that made the PCM think it was warmer than it was.

 

[Maverick909]

well damn. im watching thread to see what you come up with

 

[mwilk012]

Most Likely O2 sensor or the O2 not going into ready mode

Sensors don’t change conditions, control modules do.

 

[XxsullyxX123]

I failed to mention, but my uconnect and dash display were stuck on 39 degrees for 3-4 key cycles over the weekend which it was 55-60 degrees out. i know a lot of people have issues with that from time to time. could be related that the ambient temp sensor got stuck at 111 for the morning of my CEL. it was never 111 outside, but sitting after the car shut off would definitely heatsoak the AAT and IAT sensors until it cooled down.

 

[mwilk012]

See attached

 

[XxsullyxX123]

Awesome, thanks for that. perhaps the AAT and IAT bad readings in relation to the normal warming up of the ECT were enough to trigger the light. I see step 2 saying replace the ECT sensor, but i am sure that one wasn't the one with the bad readings, it was the other 2.

 

[XxsullyxX123]

I wonder what the Intermitten condition procedure is. Because that's clearly an issue for me. most times the IAT and AAT read correct and the CEL does not come on. it took 100 warm ups from my first reset last month to see the conditions again to trigger the CEL.

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