Check engine light

The check engine light is not on in my 2003 Toyota Tacoma sr5 4wd 4cyl manual transmission. Does this mean my catalytic converter is good? Or, could a catalytic converter be bad and not cause the check engine light to glow.

The truck is not showing a symptoms of a bad cat, but I just wanted to know if the lack of check engine light is a sure sign of a good cat.

This may be a strange question, but I just want to make sure things are working correctly.

Thanks for any replies.

 

What makes you think the catalytic is bad?

 

I noticed in some of the old maintenance records (from a previous owner) that the truck's check engine light had come on, and the dealership gave an estimate which included replacing an o2 sensor and both cats. However, only the o2 sensor was replaced. I'm not sure if it was simply not necessary to replace the cats or the owner just didn't want to spend the money.

 

If the CEL did not come back on after the o2 sensor's were installed then it probley did not need to be replaced

 

That's what I was thinking. Just to be on the safe side, I might try to contact the previous owner and check if this is indeed what happened. I know a bad cat is usually caused by another issue so I just want to make sure everything's good.

 

I got '97. Check Engine Light off and on, talk to mechanic he said if everything running smoothly don't worry about it. So I kept on going and goin'....

 

go to autozone/aamco/anywhere that offers to pull a code for free then post what it was.

CEL ranges from exhaust leak, to bad sensors, to bad cat, to bad charcoal canister, etc.

 

The CEL is not on anymore and, as far as I know, has not been on for a while.

What I am trying to determine is if this indicates that the catalytic converters are good. Could the catalytic converters be bad and not be detected by the 02 sensors? In other words, is the lack of CEL definitively showing that the catalytic converters are good.

 

Yeah, that's what I'm thinkin'. I guess if it doesn't turn back on I shouldn't worry about it.

 

if its on there is a problem. if it's off you're gravy.

 

I read the previous maintenance records a bit more and found that the codes thrown were po136 and p0420. Evidently the o2 sensor fixed it though because the lights not on anymore. I guess I'm worrying over nothing.

 

2003 Tacoma SR5 TRD V6 4x4 check engine light came on at 105,000 mi!

Is there a scheduled maintainance at 105K?