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

5TH LETTER

MEMBER
1996 CADILLAC DEVILLE
3.4L
V8
2WD
AUTOMATIC
55,000 MILES

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?

Thursday, February 4th, 2021 AT 8:38 AM

3 Replies

STEVE W.

MECHANIC
13,001 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.

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Thursday, February 4th, 2021 AT 11:17 AM

5TH LETTER

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10 POSTS

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

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Thursday, February 4th, 2021 AT 1:07 PM

STEVE W.

MECHANIC
13,001 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?

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Thursday, February 4th, 2021 AT 3:10 PM