Quiet Exhaust Mode Caused Check Engine Light

[krisk]

I had an interesting, although not entirely unexpected thing happen with my 2024 Mustang GT PP today.

I’m doing a track day at Road Atlanta, and from 10am-12pm on Sunday the county has mandated quiet hours for the track. We were still allowed to drive as long as we had a relatively quiet exhaust, and they instructed everyone with adjustable exhaust to place it in the quietest mode. Since I have the AWE Switchpath which is certainly louder than stock, I figured I better use quiet mode and not try normal. Ordinarily I use Track mode.

The first two laps were under caution and I was behind some slower cars, so I wasn’t able to go full throttle. However, on lap 3 I was able to pass and on the back straight went full throttle for about 3-4 seconds before I got a check engine light and a bunch of warnings popped up. It also cut power significantly; it was in limp mode. I made it back to the paddock without issue.

I brought my computer and adapter, so I used Forscan to pull the codes. It was the PCM with code P061C - Internal Control Module Engine RPM Performance. So obviously the quiet exhaust mode does not allow sufficient flow for use on the track. Lesson learned. I’ve since done two full sessions in Track Mode and have not had the check engine light come back on, so I feel confident it was a result of the quiet exhaust mode.

Just thought I’d share as I found it interesting.

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[A.alansari]

Shouldn't the quite exhaust open up with full throttle? it is only quite on low rpm from what i know

 

[REV745DH24]

I had an interesting, although not entirely unexpected thing happen with my 2024 Mustang GT PP today.

I’m doing a track day at Road Atlanta, and from 10am-12pm on Sunday the county has mandated quiet hours for the track. We were still allowed to drive as long as we had a relatively quiet exhaust, and they instructed everyone with adjustable exhaust to place it in the quietest mode. Since I have the AWE Switchpath which is certainly louder than stock, I figured I better use quiet mode and not try normal. Ordinarily I use Track mode.

The first two laps were under caution and I was behind some slower cars, so I wasn’t able to go full throttle. However, on lap 3 I was able to pass and on the back straight went full throttle for about 3-4 seconds before I got a check engine light and a bunch of warnings popped up. It also cut power significantly; it was in limp mode. I made it back to the paddock without issue.

I brought my computer and adapter, so I used Forscan to pull the codes. It was the PCM with code P061C - Internal Control Module Engine RPM Performance. So obviously the quiet exhaust mode does not allow sufficient flow for use on the track. Lesson learned. I’ve since done two full sessions in Track Mode and have not had the check engine light come back on, so I feel confident it was a result of the quiet exhaust mode.

Just thought I’d share as I found it interesting.

Kinda odd, let us know after further investigation, I have AWE mufflers(love the loud) along with Kooks headers! I don’t think I’ll use quiet mode ever!

 

[Sofa King]

Doesn't that exhaust have a "no check engine light guarantee"?

 

[krisk]

Shouldn't the quite exhaust open up with full throttle? it is only quite on low rpm from what i know

Ive never noticed the exhaust fully opening based on what I’ve heard from it in quiet mode. It seems that would defeat the purpose of having the different modes if it automatically fully opened (track mode) by going full throttle.

Kinda odd, let us know after further investigation, I have AWE mufflers(love the loud) along with Kooks headers! I don’t think I’ll use quiet mode ever!

I ran four full sessions for a total of almost 2 hours of driving after the CEL, and had not issues. Given no other issues I’m attributing the CEL to running in quiet mode on the track.

Doesn't that exhaust have a "no check engine light guarantee"?

It does have a no CEL guarantee, and in the year and a half and thousands of miles I’ve had it on I have never previously had a CEL. To me it makes sense that a code could be thrown when operating at sustained high RPMs and full throttle application. Given I’ve had no issues on the track previously while in track mode, I don’t consider it to be an issue with the exhaust. I expect the OE exhaust would cause the same issues since the AWE valves are being controlled by the car in the same way as stock. I don’t see where anyone could realistically reproduce the conditions I experienced on the street. It seems to be logical not to use quiet mode on the track since it is a restriction of the exhaust flow.

 

[A.alansari]

Ive never noticed the exhaust fully opening based on what I’ve heard from it in quiet mode. It seems that would defeat the purpose of having the different modes if it automatically fully opened (track mode) by going full throttle.

i remember i've seen a dyno test with quite mode on and the car was making the same power and the guy said because the exhaust will open by itself

You can try it yourself put it on quite and put a camera and rev the car you will see it opens

 

[krisk]

i remember i've seen a dyno test with quite mode on and the car was making the same power and the guy said because the exhaust will open by itself

You can try it yourself put it on quite and put a camera and rev the car you will see it opens

Interesting. So it could have less to do with WOT application and be more about sustained high RPM with the throttle in track mode. Unless it was a very odd coincidence, the car didn’t like something about being in quiet mode on the track. I was just guessing that it was the restriction during WOT application, but it’s just a guess.

 

[Zig]

Interesting. So it could have less to do with WOT application and be more about sustained high RPM with the throttle in track mode. Unless it was a very odd coincidence, the car didn’t like something about being in quiet mode on the track. I was just guessing that it was the restriction during WOT application, but it’s just a guess.

Beginning to sound more like the car was asking for clarity as opposed to indicating an error. Kinda like hey wait something abby normal happening maybe i should remind the driver to take a look (sustained high rpm is logically opposite of quite - just a checksum kind of thing). No codes, none pending?

 

[krisk]

Beginning to sound more like the car was asking for clarity as opposed to indicating an error. Kinda like hey wait something abby normal happening maybe i should remind the driver to take a look (sustained high rpm is logically opposite of quite - just a checksum kind of thing). No codes, none pending?

The only code was the P061C which I cleared. It is unusual to have the car in track mode, but then ask for quiet mode from the exhaust. I imagine that is not a routinely expected configuration.

 

[Zig]

The only code was the P061C which I cleared. It is unusual to have the car in track mode, but then ask for quiet mode from the exhaust. I imagine that is not a routinely expected configuration.

Did you get gas there or brought your own?

 

[Deleted member 63910]

Quite the quandary. Running in quiet mode, getting a check engine light while on the track. I would have been quite perturbed. Maybe the S650 is smarter than we are and it knows that on the track running in quiet mode is counter productive. I have noticed while in quiet mode it is indeed quite quiet.

 

[krisk]

Did you get gas there or brought your own?

I brought my own 93 octane from the same QT I use for every track event.

 

[krisk]

Quite the quandary. Running in quiet mode, getting a check engine light while on the track. I would have been quite perturbed. Maybe the S650 is smarter than we are and it knows that on the track running in quiet mode is counter productive. I have noticed while in quiet mode it is indeed quite quiet.

It didn’t bother me too much because I kind of wondered if there would be any issues running in quiet mode. When the light came on I wasn’t that surprised.

 

[Junkyard Dog]

Quite the quandary. Running in quiet mode, getting a check engine light while on the track. I would have been quite perturbed. Maybe the S650 is smarter than we are and it knows that on the track running in quiet mode is counter productive. I have noticed while in quiet mode it is indeed quite quiet.

Just a note - he is not running the factory active exhaust setup. His is aftermarket.

 

[Christian/AWE]

The factory system is designed with protective logic, and under higher loads, the added backpressure from closed valves can cause the PCM to intervene. This isn't exclusive to aftermarket systems—even the stock exhaust in Quiet Mode can trigger this behavior under the right (or wrong) conditions. It’s essentially the vehicle safeguarding itself from excessive restriction. As OP suggested, removing restriction will clear this CEL right away.

If you’ve got an AWE SwitchPath system and you're dealing with a persistent CEL, our team is here to support. Drop us a line with the specific code and conditions that caused it, and we’ll help troubleshoot from there. No guesswork—just real support from folks who live and breathe this stuff.

https://www.awe-tuning.com/pages/support

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