Engine Light

[lexus53]

engine light on 1993 ls400

[sha4000]

We need more info than that. Do you know how to read the codes? if not here's a link to how you do it.

http://www.lexls.com/tutorials/intro/codereading.html

[boogieman]

Most major auto supply's will read the codes for free for you if you don't have a scanner.

[landar]

Most major auto supply's will read the codes for free for you if you don't have a scanner.

Thats true in most cases and a good way to go if you do not have a scanner. Except in this case, the car in question is a 93 and before the OBDII systems began in 1996. Still, you can read the codes manually by shorting a couple of connector pins and watching the blinking lights as sha4000 pointed out.

[lexus53]

Don't really know much about cars.I haven't driven the car that much during the winter months.The other day when I drove it the indicator lights came on.The manual says that this light is the MALFUNCTION INDICATOR LAMP (h) and there is a problem with the engine electrical system.Also theTRACTION OFF LIGHT,(n) came on at the same time,this indicates a problem in the anti-lock brake system.The car seems to run fine.I read on the internet that if you disconnect the battery for 5 minutes the system will reset.Would this be alright to do. Thanks

[landar]

The manual is correct about the 'MIL' but you need to read the code from the computer to determine precisely what is it squawking about. It is good that the engine is running fine. May not be that big of a deal. Yes, you can pull the negative terminal on the battery for a while to reset BUT I would try reading the code(s) first before doing that.

[Exhaustgases]

Do not disconnect the battery till you see what code is set.

Trac light always comes on when there is a fault code, Trac turns off when there is a problem.

Get the code and lets fix it.

[lexus53]

Checked the code with the jump wire thru the diagnostic port. Code 25-(AIR FUEL RATIO LEAN MALFUNCTION.) What does this mean? Also Trak Off light just kept blinking the whole time. Could I have gotten bad gas. L Always use Premium Gas in car. Would it help if I put injector cleaner in gas tank? Thanks for all the help so far.

[sha4000]

Could be but most likely related to your O2 (Oxygen) sensor.

https://www.google.com/search?q=lexus+code+25&oq=lexus+code+25&aqs=chrome..69i57j0l5.6037j0j4&sourceid=chrome&es_sm=119&ie=UTF-8

[lexus53]

Thanks for all the info. I'm no mechanic but I learned alot with all the posts. About 2 years ago (20,000 miles) I changed Plugs,Wires,Rotors,Caps,Fuel Filter and Air Filter. Timing Belt and Water Pump were changed 75,000 miles ago. ECU Unit was changed 60,000 miles ago. I have had the car for over 10 years and never changed the Oxygen sensors and I doubt the owner before me ever changed them. The car seems to run fine. There is no difference in performance since the light came on. For the past 3 months the car has sat in the garage and would not be started for 2 or 3 weeks at a time. I'm hoping that maybe that has something to do with it. I think I'll throw some injector cleaner in the tank and after I run a few tanks thru, as long as the car is still running good, I will reset the code and see if it stays off. If the light comes back on then I'll go after the Oxygen sensors. Thanks so much for all the information.

[landar]

That sounds like a reasonable plan.

You might want to check into the MAF (Mass Air Flow) sensor as it could be misbehaving, having the computer believe that less air flow is reaching the intake manifold than there really is. Also, check for any vacuum leaks around the plenum/manifold...could be a cracked hose allowing air to bypass the air flow sensor.

And finally, check for pinhole leaks in your exhaust pipe just before and after the sensors (CAT area). Sometimes that causes wacky readings.

[LSPaul]

My own experience with that is after I had the leaking exhaust gaskets replaced on my '93 (at the cat-exhaust pipe junction), I eventually ended up having to replace both upstream O2 sensors.

Paul

[Exhaustgases]

You can check the operation of the O2 sensors with a free digital multimeter, that is if you can find a coupon for harbor freight.

And you flip open the test connector on the engine and test the OX points your looking for a fluctuating .1 to .9 or so volts.