Service engine soon light ON...
 

This light went on about a month ago, I was told by Advance Auto Parts that I had to change a sensor so I did, light still on, changed other sensor, light STILL on. What now??? HELP!!!!:mad:

wow thats a bit too vague.

You need to give us more information so members can help you out.

First off what car do you have, exact year make, model. perhaps engine.

also what exactly was the CEL code that advance auto told you. If you didn't get the code, that makes it difficult.

what sensor did you change? did you reset the ecu after changing the sensor?

My Bad....
 

I drive a Montero Sport LS 3.0 Liter, the code was PO154, I heard from someone that there are more than two sensors?? Can it be the catalitic converter?

Yes...
 

Yes, I disconnected the battery during the change for both sensors. The ones changed were Bank 2 Sensor 1 which they said was the one directly on the block, then changed the one on the manifold, is that Bank 1 Sensor 1?

Sorry, are you talking about oxygen sensors? How many miles on your beast, anyway?

And, yes, without the exact code it's all catch as catch can. More info, please, and then we can make some more informed guesses:)

Kinnoto74

First a few genreal tips. Please ALWAYS include the model and year and mileage if you want the fastest help. Kudos to redturboeclipse for taking time to ask you. (You still didn't give us the year or mileage)

Next, when you were asked if the ECU was reset I belive you answered yes because you had the battery disconnected. If I'm correct, then please know (this keeps coming up like some bad urban ledgend) that disconnecting the batt will not reset the SES light. That has to be done with an OBD code reader ($60 at most stores and well worth the cost if you're going to keep your Montero)

Finally, at the top of the forum pages there is a SEARCH link - it's there for a good reason. If you go there and then to Advanced Search and search the Montero fourms for "OBD P0154" you will get posts from many many fellow sufferers. I don't have a 3.0L engine but it appears from the posts that there is factory TSB - Technical Service Bulletin describing a known problem with that code appearing. I just glanced at the posts but it seems that the defect is cured by having a dealer download new software and that if your model has this defect your Sensors may have been fine.

Do the research and check with a dealer - if the TSB applies to your truck hopefully it's not too expensive to have your ECU upgraded.

Good Luck!

You can also read a bit about this code in general here:
http://www.obd-codes.com/p0154

Did you use those "universal" o2 sensors that you have to wire in yourself.. or the oem-type/or actual oem, where you just plug and play because you swap the entire sensorw ith the wiring and harness.

it looks like your ont he right track. after you swapped it did you check if the o2 is cycling

Jrmdir said: "If I'm correct, then please know (this keeps coming up like some bad urban ledgend) that disconnecting the batt will not reset the SES light..."

Maybe the confusion comes from the fact that on page 6-13 of the Haynes manual it says:

"To erase the ECU's memory of any stored codes once the problem is fixed, simply disconnect the negative terminal of the battery for at least 10 seconds."

This could lead one to conclude that the SES light might be reset by doing this as well. As with many things with the Haynes manual, it fails to win any awards for clarity.

If the Haynes manual is for your 1995 then that is probably correct. From 1996 on OBDII cars have varying degrees of backup EPROM voltage supplied and battery disconnect is not recommended or seen as effective - at least acording to most of the what Google returns on the subject. e.g. from Edmunds.com: That said, here's a mechanic who confirms it's not supposed to work, then says you might be able to do it - and then goes into detail why it's not a good idea. Go figure? http://www.auto-facts.org/resetcheckenginelight.html