hey, my engine light came on and the garage said that some cylinders were running lean.. so i put some ngk's in and it seemed to run better. buttttt i took it out on the highway and the engine light came on again.. any insight..
i have a 99 4runner 122000km........thanks

 

How long did it run around town without the light? Or did you take it on the higway right away? Could be the O2.

 

i was on the highway when the light came on, both times.

 

This is how this check engine light thing is supposed to work.

When the ECU thinks that there is something wrong it alerts you by turning on the light. You take it to a compentent mechanic. He does the basic checks like battery, electrical system and and few other things to make sure they are all in order because low voltage or a faulty electrical system can cause all kinds of other faults.

If all that checks out then he sees what the code is stored in the ECU. This code does not tell anyone what is wrong. The code only recommends which of the hundreds of diagnostic proceedures to run to find out what if anything is really wrong.

So lets say your mechanic did this the way he was supposed to and determined that there is in fact a fuel delivery issue. Why in the world would he recommend a spark plug change?

How much did you pay this goof???

Gadget

www.GadgetOnline.com

 

Get them to give you the actual OBD code number and post back.
Then we can start to help you troubleshoot from there.