I know it's not possible to diagnose this problem with certainty, but I'm interested in other's experiences and advice.

The check engine light went on the other day out of the blue.

'97 4Runner, 3.4, 2wd auto, 127k miles. Runs perfect, uses/leaks no fluid, no change in performance or gas mileage after light came on. After it came on, I disconnected the battery for a few minutes and reconnected it. The light stayed off for 50 miles or so then came back on.

I have complete service history for the vehicle, timing belt done at 75k miles, but no other engine work done (at least not at the dealer).

My instinct tells me it's an Oxygen sensor, but I have no way of knowing. I will probably take it to someone who can plug it in and read the code, but I thought I would check here first.

How long did your O2 sensors last? There are two, is there one more likely to cause this, or do you need to do both at one time?

What do the YotaTechers think it is??

 

We gotta have a code number to make any diagnosis at all.
Get it read by a shop or Autozone if they are still doing it for free.

 

Yeah, Autozone in my neck of the woods still pulls the code for free. If you're the original owner and you've never replaced an O2 sensor, then you're probably on target, but you won't know for sure until the code(s) is pulled. There are 1 or more lists in the tech write-up section with the codes and their meanings.

 

Didn't know AZ would scope it for free; I would have just taken it to a garage and paid for a diagnosis. That will save some time and money, thanks.

Assuming that it shows I need O2 sensors, is there an aftermarket brand of sensors that is OK (Bosch, NGK, etc) or is it best to get the Toyota ones?

 

jake,

stick w/ oem sensors. urdusa.com sells them cheap. pull the code and let us know. i have a writeup on changing 02 sensors. look in the tech section. and as always, search!

bob

 

Most auto places will do it for free these days. Most will _not_ clear the code though. You can do that yourself as you found by pulling a battery cable, or you can just pull the "EFI" fuse that's in the box under the hood for a few seconds.


Front one only (97.8% of the time), use only OEM, and the best prices we've found are from URD USA:
http://www.urdusa.com/product_info.p...s_id=430006000

 

Gotta love the internet. I'll get the code and order the sensor if I need it. Thanks again--excellent forum.

 

Follow Up:

Went to AutoZone and had them plug in the OBDII meter to get the code. Their meter gave me not only the raw code, but de-coded it: PO133; Slow response Bank 1; Sensor 1, O2 sensor. Front O2 sensor bad. Had the guy clear the code.

Went to dealership and they quoted me $140 for the front sensor. I told them I could mail order it for around $100 (as I learned here, from URD.com. They ended up selling it to me for $118, which he said is wholesale. I doubt it is, but I wanted to fix the truck that day and not wait for shipping from URD.

Installation took all of 10 minutes. I figure the mechanic would have charged me full retail for the part and at least an hour of labor for diagnosis and replacement of the sensor. I saved at least $100 doing it myself.

Truck runs smoother, has more power, and appears to be getting significantly better mileage. Thanks yotatech forum!