XPY

My 99 4Runner Engine Light keeps coming on. The only thing I've noticed is that it seems to come on after the fuel gauge shows half full. After checking as much of the wiring for any loose connections, making sure the gas cap was tight, I'm not sure what else to do. If I fill the tank up the engine light will go out within about 5km.

I've been told that I should check the MAF sensor and possibly clean it, but I don't see what that has to do with the fuel gauge.

I don't have a BR-3 OBDII systems analyzer or the windows software to check what the error code is. I live in Burlington, Ontario anyone close have one?

Once I figure out what the problem is I've read I can un-hook the battery to reset the codes, but I've also been told that by un-hooking the battery on some cars with air bags you permanently disable the air bags. Someone else mentioned just pulling the EFI fuse to reset the codes.

Anyways I need to figure out what the problem is first.

Bob_98SR5

fuel gauge problem related to TSB EL010. search the term. there is a ton of info on it on the forum.

and we can't help you without a code reading. best to find one or get it pulled and then we can help

bob

MTL_4runner

You need to either get a code reader (they are as cheap as $50 USD from Harbor Freight) or take it to a shop and have the codes read for you before anyone on here can help you. There is no sense taking pot shots in the dark util we have something to diagnose from. The fuel tank issue could be coincidental or it might not.......need a code to tell for sure.

There are two ways to reset the ECU for OBD codes, pull the negative terminal or pull the EFI fuse and neither will disable the airbags.....not sure where you got that.

XPY

Do you have an Autozone nearby? They check codes for free.
It almost sounds like its got something to do with the air pressure in your fuel tank.
If you are below 1/2 tank and take the gascap off and release the built up air pressure, does the light go off?
Either way, Id plug an OBD 2 scanner in and see what codes you fine.

XPY

Not sure if their is an AUTOZONE nearby but I'll check. My Toyota mechanic told me it can take a day or two for the engine light to go off even though the problem has been fixed. The gas cap pressure seems to be good when I refuel at half a tank.

I've also been complaining about a jerky hesitation in my truck ever since I bought it off the dealer. They made a note of it since it was under warranty. They always told me to bring it in if does it. Problem being it has to be a really damp foggy, rainny day and the truck would only do it if it was from a cold start. Then it would clear up and go away. It would also only happen between 2 & 3 thousand RPM's. I've had this problem with domestic trucks it's always turned out to be a distributor problem, or the wires too.

Was wondering if this, a distributor or wire failure, could cause the engine light to come on?

MTL_4runner

Nope.....no Autozones in Ontario (or even in Canada I think).

The OBD codes may reset by themselves but yes it would likely take some time to do so. Usually if you replace a part you reset them manually by pulling the ECU fuse or negative battery terminal. There are a huge number of things which can cause a CEL, you really need to get the actual code numbers because otherwise it is a waste of time to hypothesize about what might be your problem. Have your toyota mechanic pull them and then post the code numbers.

XPY

Ok so the OBD II code for the problem with my 4Runner is P0172

MTL_4runner

Ok, perfect.

There are typically 2 things that it could be with that code. Either a MAF sensor or an O2 sensor. Typically you would first try to clean the MAF sesnor according to this:
http://www.4x4wire.com/toyota/mainte...tenancep5.html

Then reset the ECU (as mentioned above). If the code comes back then you may need a new MAF sensor. You can either try to get a used one (from a junkyard) or buy a new one from the dealer. Replace and reset again. If you still have a CEL after that, it is likely that the O2 (actually an A/F sensor on your year vehicle) sensor is bad and will need replacement.

Toyofast

Before taking the truck anywhere, check your gas cap. Make sure it's on tight and correctly. A loose gas cap will cause you problems. Toyota fuel systems run off a decent amount of vacuum pressure... most people replace the gas cap and problems go away. Don't use those aftermarket locking caps either... if Toyota doesn't recomend them, don't use them. I work at a dealership and have to deal with small things like this everyday.

MTL_4runner

Are you a mechanic at this Toyota dealership?

XPY

I took off and cleaned the MAF sensor and PVC valves myself and I'll clean the throttle body out on Friday, probably replace the plugs while I'm at it. Not sure if I’ll bother doing the gas filter someone told me it's in the gas tank?
So far so good engine light has gone out. Picked up an OBDII code reader with the Windows software to get the problem code and reset the computer. So far it's cost me $250.00 total beats paying the dealer $1000.00 and I know those guys.

This site was lots of help http://www.4x4wire.com/toyota/mainte...tenancep5.html

Toyofast

Nope.. I just work in the parts dept



XPY.. how many miles do you have on the 4Runner? Is it time for any major services? 30K, 60K, 90K ??

cruzin1a

Another point, running out of gas will also trigger it. I just recently dealt with it and I cleaned the MAF according to the website listed above and it worked like a charm. The light has been out for almost two weeks now and I got my sticker.

MTL_4runner

Glad to know it worked.....post the code you get with your OBD scanner if it comes back.