I am using 93 octane and have Flowmasters axle-back. Could either one be the cause? I have used 93 octane and had aftermarket catbacks on previous GTs and Mach 1 without any problems.

TIA.

 

Don't remember anyone saying they had issues with the Flowmasters and the CEL.

Why are you running 93 octane? The brochure says 87 is just fine

Burn a tank, switch the gas and see if it goes out. You may want to reset the computer to clear the code.

 

93 & Flows won't cause a CEL. Check to make sure your gas cap it on tight.

Paul

 

Also some TSB's which may help....

04-26-22
MALFUNCTION INDICATOR LAMP (MIL) ILLUMINATED WITH MULTIPLE DIAGNOSTIC TROUBLE CODES (DTCS) P035X AND NO DRIVEABILITY SYMPTOMS - 4.6L 3V ENGINE

04-16-1
ENGINE MISFIRE OR ROUGH RUNNING - COIL ON PLUG (COP) IGNITION SYSTEMS - WDS COP KIT DIAGNOSTIC TIPS

Also, a post on the CEL said they were experiencing rough running because of a cracked plug, coil over needed replacing....

 

Have you over filled the gas tank by any chance ??

I did once, trying to put as much gas in as possible and to get the $$ at a even # on the pump. In doing so, I over filled the tank and some gas ran out.

When I cranked up to leave the station, the CEL light was on. I thought crap whats up with this. Took it to the dealer the next day & told them what happened. They said it happens fairly often, nothing wrong, that the CEL light will go out when it gets to 1/4 tank of gas. They didn't even check the car. Sure enough, at 1/4 tank, the light went out.

 

I too have the Flowmasters and 93 Octane, no problems here.

 

Ive been using 93 Octane on the stock tune for 2k miles and have had no cels

 

The error code turned out to be the sensor for the fuel tank which sets off the check enging light for the gas tank being too low or too full.

In this case it was too full. My bad. The pump keep stopping and I kept pumping fuel all the way to the top. This has been my habit with all my previous Mustangs. I'll just have to be more careful.

 

That's kind of odd. I always top off my tanks and have never had this issue. However, now I may be cursed to experience it now that I have read about it. But at least I'll know whats going on I guess.

 

I always top mine off too and never got the light. I dont think I would run 93 octane fuel without getting a tune. I heard high octane fuel burns slower than 87 and can cause other undesirable codes. You might want to check up on it some more though. Good luck!

 

I top off all the time and no codes... mmm...