Check Engine light w/ 4,300Miles

[gerrygmendez2]

Looking for some insight. I purchased my first ever mustang back in October of 2023. Once I saw the new Dark Horse I fell in love with it. Since then on September 10 2024 @ 3200miles I had a Whipple Stage 2 Supercharger kit installed. Now in April 2025 @ 4000miles I have a check engine light w/ a P0430 code stored. I tried clearing the code but it reappeared after a few drive cycles. Looking at O2 sensor data proves that the catalytic converter is not working as it should. I took it to my local dealer and they denied a warranty claim due to the supercharger being installed. When I pressed them for data the technician stated fuel trims and a/f sensors are within spec. There is no Fuel/Coolant smell in the exhaust nor is there any drivability concerns. Has anyone else had this issue with a Whipple supercharger on the new S650 or did my vehicle come with defective catalytic converters?

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[broncoboy22]

I’ll let the more experienced folks chime in. But I believe it’s expected that stage 2 Whipple kit would blow through your stock cats. Contact Whipple and see what type of mods they recommend to fix it.

 

[Billycar11]

this is why i did stage 1
it is likely it blew apart the cats do you see white powdery residue in the exhaust tips like this:
https://www.mustang7g.com/forums/threads/smoke-at-startup-reving.164389/

sadly you do have no warranty in this case its very likely caused by the extra power

 

[ShadowCoyote]

Did you have your supercharger installed at a Ford dealer? I thought dealer installed whipples come with a 3/36 warranty.

 

[broncoboy22]

Did you have your supercharger installed at a Ford dealer? I thought dealer installed whipples come with a 3/36 warranty.

Only stage 1

 

[Skye]

For reference, I'm attaching some photos:

- A S550 GT cat, just starting to crack from boost pressure

- A S550 GT cat, cratered

- A comparison of a non-boosted, F150 and GT500 cat. Notice the design allows for increased flow

If cat failure is confirmed, that is not an unusual condition. Some re-fit GT500 cats to their exhaust. Others, remove them all-together.

Those with boosted setups can provide guidance as to what has worked for them.

 

[Q6543]

The first thing I did was get them outta there, cats and boost are just a terrible idea.

 

[Richard mcswiney]

I went with kooks long tube headers and green cats. I did the stage 2 as well and the performance shop said at install to due both or expect the cats to go. I have no check engine light with this setup

 

[Q6543]

Aftermarket cats seem to clog as much if not more than OEM

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