Multiple codes on tuned/modified GT Premium

[GregR]

New to me 2019 GT Premium has these codes. I've researched them individually but I'm wondering if collectively they mean something. Before I start diagnosing them one-by-one, I am checking to see if anyone knows if ithey could be from one source.

P0171
P0420
P26C5

JLT Cold Air Intake
Kooks long tube headers
Borla Atak cat-back
Bama tune

Sponsored

 

[WildHorse]

I'm betting an header/exhaust leak on bank 1.

 

[17MagMetal]

Do you have any warranty/leverage to have the prev. owner/dealer take care of this?

Seems to me the erased trouble codes before handing it off to you.

 

[GregR]

Purchased it about 3 weeks ago from a private party so no leverage. How do you know the codes were erased?

Recommendations on where to start looking for the leak?

 

[17MagMetal]

Purchased it about 3 weeks ago from a private party so no leverage. How do you know the codes were erased?

Recommendations on where to start looking for the leak?

Truthfully, I don’t!

Gut tells me codes were erased before you got the car. You drove it, all OBD monitor tests were ran by the car, and bang o2 sensors got a funky reading leading to codes.

What I “think” is irrelevant now though, I agree with Wildhorse and would take a look at any potential leak points upstream the o2 sensors.

It’s a shot in the dark, but I would personally also pull my spark-plugs after getting a lean code of any kind. They can often tell a story themselves.

But i’m just a shadetree scumbag, some of the other, more experienced posters here might have some more insight and can probably dive into real diagnostic procedures for this using live data.

 

[tdstuart]

Purchased it about 3 weeks ago from a private party so no leverage. How do you know the codes were erased?

Recommendations on where to start looking for the leak?

There is a parameter that I think shows time since last code clear. Don't know if your scanner can show it though.

And as for the leak if its reading too lean and its an exhaust leak it would be anywhere from the start of your headers to where your first o2 sensor is located. Anything after the first o2 sensor will not affect the cars readings. Check for bad gasket, loose clamps, punctures, etc.

As for the catalytic converter codes they probably just deleted the catalytic converts and the car is detecting that and throwing codes.

P26C5 is probably because the car had active exhaust from factory and the aftermarket one deleted the active part causing this check engine light.

What you should also do is see if you can pull up your fuel trims so you can see if at least bank 2 is running good. If bank 2 and bank 1 are off then its possible the car just needs to be retuned.

Also with the lean code don't do any pulls! Don't wan't the ecu to mess up fueling and cause a serious engine issue.

 

[larr12]

Like TDstuart and Wildhorse mentioned..

P0171 I would start double-checking the JLT clamps/hose for any leaks.

P0420/P0430 The Kooks are catted? Check the 02 sensors. If there are not cats, then you will have the codes.

Last thing, I would get a tune from @Wengerd Performance

 

[TonyNJ]

P26C5 Valve A is just one side of your active exhaust. If the AE is working, just clear that code. The code probably popped up during maintenance. If your AE isn't working, check the actuators and harness near the mufflers.

Edit: Reread your initial post. Sounds like you know how to trouble shoot that code, sorry for stating obvious.

 

[GregR]

A check engine light came on when I test drove the car. Seller said it was probably because he had just turned rev match on. He later checked and said that's what it was, and turned off Rev Match and it went away. Now I'm questioning this. Either way, that's behind me, I can't do anything about it.

 

[GregR]

Last thing, I would get a tune from @Wengerd Performance

I emailed him earlier this week after reading a thread on here. He can do a tune for me using the existing Bama tuner. Should I get these issues resolved before I do that? Well his tune override the Bama tune?

 

[larr12]

@GregR Yes, make sure you dont have any leaks issue and check your 02s.

After that, Wengerd will take care of you.

 

[Kabayo]

New to me 2019 GT Premium has these codes. I've researched them individually but I'm wondering if collectively they mean something. Before I start diagnosing them one-by-one, I am checking to see if anyone knows if ithey could be from one source.

P0171
P0420
P26C5

JLT Cold Air Intake
Kooks long tube headers
Borla Atak cat-back
Bama tune

Maybe the previous owner had this as an ongoing problem and sold it because he was tired of dealing with it. I hope you can sort it all out.

 

[GregR]

Maybe the previous owner had this as an ongoing problem and sold it because he was tired of dealing with it. I hope you can sort it all out.

Yeah, he came across as a honest, sincere, trusting guy, I sure hope not.

 

[Goterr0r]

If i was going to dump a car with issues, i would be honest and trusting appearing as well. Hope all the best for you, but if it has a Bama tuner on it, then 99% chance he didn't know too much about what's best for his car.... 30 sec site or google search will show they are basically the last option when getting a tune on a s550. s197 back in the day maybe... but not this platform anymore.

Start with the basic maintenance as you learn the car. Focus on your o2's and hunting for a vacuum leak as well as they can cause some of those codes.

 

[GregR]

Thinking on this more this could have been from me. The car sits low, it has aftermarket lowering springs, front lip is 4 in off the ground. I couldn't initially get it into my garage because of the angle of my concrete entrance ramp. I recently had a concrete guy tear out the ramp and flatten it out more with a new one. The first time I tried to get the car in after that I heard scraping. I stopped to check and it was the exhaust closer to the engine, not at the rear. I made some adjustments and was able to get the car in the garage with less scraping.

I wonder if this jolted something.

Sponsored