My check engine light came on AGAIN last night. I have a 1999 SR5V6 and it has 80,000 miles on it.

The check engine light came on when the 4Runner had 45,000 miles on it. I took it to SEVERAL dealers and finally one service manager had the experience and changed out the MAP sensor and it took care of the problem back then.

NOW, it's on again. What the heck is wrong with this thing coming on again?

Any help would be appreciated on this one. Thanks.

 

Obviously something is triggering the light to come on. What's the code that it gives you? You can pull codes for free by taking your rig to any autoparts stores (lately most carry OBD II readers) and they'll pull the code for free. You didn't just fill up recently did ya? DId you forget to tighten the gas cap correctly? THat is one of the most common CEL cases.

 

It is probably not the gas cap problem. I always make sure that I tighten the cap until I hear several click click clicks.

Thanks for the advice; I will take it to the auto parts store to read the code.

 

You need to get the ODB codes pulled on the truck and post the numbers.
You can pull them yourself with one of these as well:
http://www.harborfreight.com/cpi/cta...emnumber=46030

......or go to a local auto parts store that will do them for free.

 

Any idea where the OBD diagnostic socket exists on a 199 4Runner? In other words, once I get the OBD II reader, where in my car should I plug it in?

 

The autoparts store can find it for you, but I think it's underneath the driver's side dash. It will usually be something like a 16 pin connector.

 

I thought you had to pay for getting the codes read in California ??

 

What do you mean "have to pay"?

 

Wow....

 

No no no...come on now don't be spreading rumors on the internet

 

I'm thinkin O2 sensor...judging by the miles, just a guess though.

Fink

 

Mine went on last month at around 90k, and it was combination O2 sensor and throttle pos. sensor. Then went off after 4 days. I guess it healed itself. My Runner loves me!

 

Are you sure your 4Runner just didn't reset the check engine light?

 

it doesnt "reset" it. it stores the code as a history or pending code if the light has come on and is now off.

 

Better known as a "soft code" as they call it.

"Hard code"s keep the CEL until the problem is aleviated and the light is reset.

 

prolly just a O2 sensor..mine has done it 3 times

 

Went and got my OBD II code read. It read: P0171 = "Running Lean".

Any idea what the heck this means? Thanks.

 

means you're running lean...

In other words, not enough fuel is in the air/fuel mixture entering the cylinders. Essentially I haven't gotten to the fuel emissions course yet, but generally the manual (well at least the ones from the dealer) have a flow chart in them to follow and they usually consist of measuring various sensors within the chart and usually one of the items is at fault. Maybe someone here can post a simple flow chart or perhaps someone from around the Bay Area can give you a flow chart off a factory manual to follow...also this means that it's time to bust out the old DMM (or digital muti-meter).

Just to give you an idea, here's what the Tundra manual says (for a 5VZ engine which is the V6 engine also in 4Runners)
1) Air Induction System problem
2) Injector Blockage
3) Mass air flow sensor
4) Engine coolant temp sensor
5) Fuel pressure
6) gas leak on exhaust system
7) open or short circuit in heated oxygen sensor circuit (the sensor off the manifold)
8) PCV valve and hose
9) ECM

 

Maybe it's just time to bust out the wallet and get me a brand new Titan.

 

Like Toyota4life said it might be a o2 sensor. About a week after I exchanged my cat convter for a Fireball. MY o2 sensor blew out, I havent replaced it yet. Haven't found a cheap one. When I took my sensor out to look at it, it was black.