Idiot light question from an idiot (1 Viewer)

[Keep]

The day before I was due to go on a 2000 mile trip with my ’94 the Check Engine light came on. I dropped by the local dealer to pull the code. It indicated an O2 sensor needed to be replaced, but it was on backorder with no way of getting to me before the trip. They assured me it would be ok to drive that distance, so I planned to have the work done when I got back. During the trip the light went out. So here’s the question.

Does it simply reset or has the computer stopped sensing the problem?

 

[Grolar]

Hi - Dunno if it might be helpful, but I had exactly the same problem on my '94, the ECL with O2 sensor code came on... and off a bit later. Since then, I drove 400+ miles and it never lit back. My feeling is "if it's not broken (anymore), don't fix it", but that could be an idiot decision from an idiot... Did you try the "paper clip trick" to check if the code was still there?

 

[tech_dog]

When my O2 sensors went out, I first had intermittent CEL where it would come and go after I stopped and started the engine. Eventually it became permanent.

I'm guessing you can get intermittent O2 sensor failure before you get total failure.

 

[cruiserdan]

89465-60110. I have 3 sets in stock at the moment. When do you leave?

 

[tevogel]

hi dan

glad your back to work! thanks for finding my check and sending the alternator

 

[archie]

I think you should try to change it before you leave. You might be better off by getting more MPG and costing you less for fuel.
The CEL code is still there.The paper clip diagnostic test connections are in some thread. Try doing a an advanced search in the 80's section using key words such as "CEL dianostic jump"or "93 or 94 CEL".

 

[Keep]

Sorry I wasn't more clear in my original post. This happened 10 days ago. About 1600 miles into the trip the light went off. I'm trying to decide if I should still replace the O2 sensor or wait to see if the computer detects the problem again.

I'm not familar with the paper clip diagnostic test, I'll do some searching, thanks!

 

[cruiserdan]

If the ECU was not powered down the code will still be there. You could pull the codes and see if there are any present. If not, the code was cleared. If so, you can clear it by pulling the EFI fuse and leaving it out for about a minute.

O2 sensors do not heal themselves so the code will return at some point. You could again re-set it and repeat. The codes will show up more rapidly as time progresses.

 

[Doc]

Since you know the problem is there, the proactive thing to do would be to purchase a replacement to have on hand when it finally 'gives up the ghost'.

 

[Tentsontop]

I could say something about my experience w/O2 sensors, but don't have any wood to knock on at the moment. ;p

 

[MH_Stevens]

Did you gas consumption drop? Normally if the O2 sensor is really bad gas efficiency will suffer. My own feeling too is that a long drive where they get really hot might have some "cleaning" effect. I've know a bad O2 sensor get better after a long trip. Don't know if there is any reality in this though.

 

[MTBGUY]

From my O2 observations, I agree with Cdan and the above post.

Mine seemed to be intermittently bad at first, then progressively would set the code PO420 off with increasing frequency. I DO believe that longer drives (where they get to burn more crud off) seem to do them some good. Mine were throwing codes the most when most of my driving consisted of shorter trips.

But the good news is that when you replace them it should be worth another 2 MPG (in my case). They will pay for themselves at some point in the next year or so. I would definitely stick with the actual Toyota part on based on the many problematic posts from people that tried to use generic aftermarkets.

Buy them from Cdan instead of the local stealership!!!!!!!! I'll never buy locally again!