Yesterday when I started my Infiniti I30 the Service Engine Soon light came on and has stayed on since. My wife had recently driven the car and I noticed that she had filled the tank, which I don’t think she has ever done before. So I asked her which octane gas she put in, and she said 87. It’s not knocking or pinging; it’s hard to tell if it’s running differently because now I’m actually listening to it when I never really did before. The book says to put in Premium but when I bought it the guy told me that 89 octane was fine, and it’s always been fine with 89.
The question is, could the 87 octane gas be the reason that the Service Engine Soon light is on?
First of all, do not ask any at the Infiniti dealer if this is the reason. I can almost guarantee they will say yes, and it becomes your problem (if your car is under warranty of some sort, if not it is your problem either way). All of my cars require premium gasoline, but sometimes I will actually slip in some unleaded. The only thing I have noticed is lower performance, and sometimes a slight ping, which you say you have not noticed. IANAM, but it IS possible that your car has some sort of reader that detects bad gas in general.
Have you tried refilling the gasoline with 91 or 93 octane to see what happens?
If your car has a knock sensor, it may be able to adapt to the lower octane. If not, the timing will be set for 92 octane which burns more slowly than 87. They probably don’t set the timing on the bleeding edge of pinging so you have a little room to play with, but 92 to 87 octane is more than just a little.
Also, some cars designed for premium have an octane plug you can pull to run regular. My Supercoupe has one, although I would never put 87 octane in a car with a roots blower anyway, and I would recommend putting in whatever gas the manufacturer requires. They decide based on the compression ratio and whether or not it has forced induction. They’re not just trying to help the oil companies make more money. The octane plug is mainly for when you have no choice, ie you can only buy regular.
A steady Service Engine Light is an indication of a problem with the emissions control system. Emissions problems with lower octane fuels are generally also associated with knocking or pinging, though.
The check engine light came on because it detected a knock. Octane boost (not the whole can either. That could burn the top of the piston head) will help the gas burn cleaner.
The best option would be to run it half out or so and then top it off with premium. Then go and get the light reset. Sure you might have to pay a bit for the labor but who cares? Your car will be running good again.
No, I’m not a mechanic but I have access to them. I got the octane boost idea from a guy who messes with older cars. The half tank and reset idea is from a guy who services modern cars. He warned about not using too much octane boost.
Either way, the light will probably have to be reset at the garage. It probably won’t go off by itself.
Much better Ross Grumet, however, I am not sure about the light having to be reset at the garage, although I am neither a mechanic nor a specialist in Infinitis. If the reality is that the reason for the Service Engine light being on is the lower octane fuel, I would think that it should reset itself once the octane level evens out.
Don’t Call Me Shirley, I hope your car has no serious problems and look forward to hearing the outcome.
Sometimes a google search on DIY “check engine light” reset is in order. One car make, for example, merely has a switch that is uncovered by removing a plastic kick-panel on the drivers side, for example. If you know the light has illuminated for something silly (like a loose fuel cap) then this might be an option, rather than pay the drones $100 to push a button. I suspect an infiniti might be a more involved affair, who knows.
Something else that can cause problems, and which many don’t know, is overfilling of the tank; you know, continuing to squeeze the last drop in after the auto shutoff has stopped the filling? Ask her if she did that (nicely, of course).
I’ve gotten a lot of peace of mind from a little tool I bought for my BMW that tells me what the “check engine” light means, and allows me to reset it. Once, I got a random hit on the O2 sensor, so I reset it to see if it ever came back (it didn’t), and once I didn’t have my gas cap on tight, so the fix was obvious. I also figure if it ever ends up being something I have to take the car in for, I’ll already know what the engine is telling the mechanic before he checks it, so if it says my O2 sensor is bad and he tells me my 3rd Fetzer valve is shot, I’m a step ahead ;).
It cost about $100, and was made by Peake Research, but I notice they only seem to make tools for BMWs. Maybe you could find something like that for the Infiniti.
AutoZone and many other car partsplaces will let you borrow their code reader for free to read the codes from any car made in 1996 or later. Go there, get the code, and see what it says. If you post it here, we might even be able to tell you what it means.
I think this post illustrates nicely that the generic “Take Car to Dealer Now” lights are a real problem, albeit one would think our already-stuffed brains could handle just a bit more specificity as to the nature of the problem. With commercial GPS and Onstar - why not upload a continuous data stream to the dealer? Lots of agricultural equipment will send a “help I’m broke” signal to by golly knows somewhere, (so eventually the mechanic who is dispatched pretty much knows what he’s getting into. A lot of people don’t have the time or, inclination to be a car mechanic, but everyone would benefit from knowing what’s really wrong, whether they need to have their car checked out right away, or put it off a week or so to more convenient time or place. Side question: Do any cars run windows or software that might crash, or is it all ROM based? I hope that’s not a stupid question.