Jerseyguy

Hello all,

This is my first post though I've been a long-time lurker. Thank you to all who contribute to this forum, it's really saved my sanity (and wallet).

I'd appreciate any advice or opinions on the following situation:

Six months ago, I took my '02 RX300 (currently has 104,000 miles) to a local tire/maintenance chain for a simple oil change. I've been using them out of convenience, despite the fact that they are always calling to tell me something else needs done--for additional $ of course. One example of their "helpfulness" occurred during a previous oil change when they told me my cabin air filter was dirty and asked if I wanted them to change it. I didn't ask how they happened to notice this while performing a simple oil change. I never take them up on their additional services.

A few days later (after driving about 60 miles), the check engine light (CEL) came on. It had never come on before in the five years/65,000 miles since I've owned the vehicle.

The codes were: P0440, P0441, and P0446. Thanks to this forum, it (luckily) turned out to be a disconnected hose at the back of the air filter housing. I'm 99.99% certain that the mechanic at the shop was trolling for additional services to perform, looked at the air filter but didn't realize he had disconnected the hose. I said nothing to them. I reconnected the hose, erased the codes, and all was fine--until now.

Call me crazy but last week I took it to them again for a basic oil change. (I told you they were convenient.) Sure enough, a few days later (after 75 miles of driving), the CEL comes on. I immediately suspected the hose to the air filter housing but to my surprise, it was connected. So I hooked up my code scanner and got code P0136, the O2 sensor (bank 1, sensor 2). Thanks to this forum, I learn that it's underneath the car, attached to the exhaust pipe, then up to a connector under the driver's seat. I got underneath the car for a quick look but it doesn't appear to have been messed with or otherwise damaged (at least to my untrained eye).

My questions are:

Is there any way the mechanic could've accidentally damaged it? Or worse, intentionally sabotaged it, hoping I'd bring it back for them to diagnose and fix? Is there anything else that could throw code P0136? (I've searched the forum and this one seems pretty cut and dried.) Is there a simple way to diagnose the sensor (with a multimeter?) to see if it's really failed? Alternatively, could it have some sort of dirt/grime buildup and be restored by cleaning it with something?

I realize that it could just be an incredible coincidence but I have my doubts. For the moment, I erased the code but haven't driven it yet.

Thanks in advance and best regards.

Carver

At 104k you are ripe for an 02 replacement. I wouldn't try to inspect it or clean it, just face the fact it's time to replace it. I would suggest staying with the OEM Denso part, they are available on line.

thomas1

you can find them on Amazon for the denso one.

code58

The one question I have to ask (I know, you've already said it was because of convenience) why ANYONE EVER takes their car to a "tire/maintenance chain" for an oil change. Maintenance is a "HOOK", not a business in and of itself (they don't give a "rat's patoot" about the oil change), they want to get their grubby hands on your car to see what they can sell you and make some REAL money on. EVERYONE who works in those places is TRAINED to do that, if they don't bring in the big bucks selling you stuff that is of questionable quality and often questionable whether you need it or not, they're not going to be working there long, PERIOD!!!
My widowed sister-in-law took her F-150 to a quick oil change recently because I wasn't feeling real well (I normally do it for her for the $23.-$24. in Motorcraft oil and Motorcraft filter from Wally World) and came out with a $180. bill that she couldn't really afford. If that wallet is weighting you down, they will certainly help you with that problem, and be sure to send you a notice the next time they thing you may have that problem, which will be soon!!!

thomas1

Well said Roger, You and I are fortunate, because we understand, but a lot of folks dont know anything about their cars...I try to tell people to use these sites, it educates them to make a more informed decision when dealing with mechanics, dealerships, ect. I wish these sites existed a long time ago, it certainly has saved $$$ for people...

code58

You hit the nail on the head Thomas. I have told my grandsons AND granddaughters to educate themselves about their cars, even if they NEVER plan to work on them. An educated customer IS NOT what those places want to see come through the door. An un-AUTO-educated one is what they salivate over. Thank God for the forum sites, they not only help those that do their own work, but educate (empower) those that HAVE it done. I spent a good deal of my life in automotive work and always HATED to see people get ripped off! Sometimes you want to see those kind of people get cuffed and stuffed (in the seat of the local "black and white taxi") It's robbery without the aid of a mask or gun!

Jerseyguy

Thanks all. The CEL came back on after 25 miles. Same code, P0136. I guess I'll replace the sensor and chalk up its failure to an incredible coincidence, though I'm done with those type of repair shops.

In my defense, I only used them because I don't have a garage, park in a dirt/gravel driveway, and the ripoff shop is only one block away--while the dealer is a 20 minute drive (with no traffic), more like 30-35 minutes at rush hour. Plus, access to that darn oil filter is a PITA!

Ok, enough whining. Thanks again to all but especially to Lexmex for the excellent DIY write-ups and photos. With them, even a klutz like me stands a chance of getting it done right the first time.