Can putting a lower than recommended octane fuel cause Check engine light?

1996 CADILLAC DEVILLE

55,000 MILES • 3.4L • V8 • 2WD • AUTOMATIC

5TH LETTER

MEMBER
10 POSTS

And you were running low on fuel due to oversight, so you had to put a lower octane fuel in your car than recommended. Could that potentially trigger an intermittent check engine light, possibly with an associated transmission related code?

Feb 4, 2021 at 12:38 AM

STEVE W.

✓Experienced Mechanic
15,330 POSTS

Could it possibly trigger the check engine light? Maybe if the fuel was really junk fuel that was contaminated with water or dirt and caused an issue with plugging an injector or fouled a plug. However, it would be a real long shot, if it was something like 87 octane decent fuel the engine management system should drop the timing and adjust so it runs okay. It wouldn't trigger a transmission code though.
If you post the codes we might be able to give you a better idea.

Feb 4, 2021 at 3:17 AM

5TH LETTER

MEMBER
10 POSTS

The only code I’ve gotten is P1707, IIRC.

Feb 4, 2021 at 5:07 AM

STEVE W.

✓Experienced Mechanic
15,330 POSTS

Hmm, don't see that code listed for your car. I see a P0107, P1107, P0171 The first two are MAP low voltage related and the P0171 is a fuel system lean code.
P1707 as a generic code does exist but it's not going to show up on your car as it isn't a 4X4 with a transfer case.
How did you get that code?

Feb 4, 2021 at 7:10 AM

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