Hello all,

I'm halfway through a 1600 mile road trip in my 2001 i30. Got an SES so I pulled into a local Auto Zone and asked them to pull the code since I don't have my scanner with me. Turns out it's an O2 sensor, but I didn't think to ask/remember which one. Oddly enough, I got this SES immediately after stopping for gas, which made me think it was a loose gas cap.

The car seems to be driving fine, and MPG is pretty consistent. First tank of gas (25% city, 75% @70 mph) got me 22.7 mpg, second tank (all highway at 75 mph) got me 24.9, and the third tank (80 mph) was 23.8 mpg. I like that the further west you drive, the speed limits are higher!)

My question is: Can I safely make the return trip (800 miles) with a bad sensor, or will this cause chain reaction problems? I remember reading about failing IACV's and such that take the ECM down when they go. I've only had my i30 for a few weeks so I'm still learning.

If I have it repaired here, I'll likely have to pay a mechanic to do the job, but if I wait until I get home, I can do the job by myself.

Note to moderator: is it possible to add "o2" to the search terms? I tried searching this on my own but got an error saying that o2 was too short of a word!

 

If it was a front sensor, then you might experience performance issues, but a rear sensor will typically not affect anything. Either way you will probably be fine for the return trip. Just get it fixed when you get home.

 

Went back to the parts place and asked them to pull the code. Turns out it was this:

P0138 - Bank 1 Sens 2, High Voltage

I thought this was strange because according to the stack of dealership receipts the previous owner just had them all replaced (which I also think is strange because the car has only 61k on it.) I did a little song and dance to the parts store guy and said "Yeah, I was untangling a plastic bag out of the radiator fan and unplugged that wire, then forgot and started the engine. Clear it for me, wont'cha?" Must have been an odd fluke or something because 100 miles later, still no light.

 

Those rear sensors take a while to trip off a ses light when they just begin to fail. It can come on at any time but the rears are not a big deal to drive on as others have said. It will turn back on though.

 

ive been driving on a faulty rear O2 sensor for 6 months. no big deal. just replace it when emissions time comes.

 

No big deal, you will just fail emissions

 

Made it home, everyone was right -- no worries on driving like that. And, as predicted the light came on after 100 miles or so.

I've been doing a lot of searching to find a good place to buy a new sensor and I've seen a lot of posts suggesting that people test the sensor before just replacing it, but I haven't been able to find a testing procedure. Anyone have a favorite method and online store?

I did find this site: http://www.oxygensensors.com/catalog.php?&pkey=1373464 and of course if I went here I would go with the non-universal one so I'd have plug and play -- however I have that fear of getting what I paid for.

How do we feel about this store?

 

Oxygensensors.com is a great place to buy them. Actually the Bosch sensors are available at AutoZone also, for a similar price. Yes, get the plug & play, you won't be disappointed.

And forget the testing ritual. Nice thought, but trust me. These things are a wear item, and go out on a regular basis. Sometimes testing doesn't reveal the cause while in operation. It's a 5 minute install. Be happy.

 

That's sort of what I was thinking too. My only wondering was that if the codes got crossed up somehow like bad O2 meant that the AFM was sending bad fuel, etc.

OK... so I'm going to show my work here and make sure I diagnosed correctly. I do want the OEM-style. I've experimented with the universals in my Miatas and they didn't work.

My codes (just got home and checked with my scanner, now there are two) are P0138 and P0139, both of which point to Bank 1 Rear sensor two, which is the rear/right downstream of the cats. The site identifies this as the Post-Cat Rear.

If I'm reading everything correctly, I need the post-cat rear, Walker OEM part number 250-24286, yes?

 

just buy it from courtesy parts or infinitiparts usa. Just go OEM, that way you dont have to splice wires or do anything complicated. Just plug and play.

 

I'm all about plug and play -- isn't the Walker OEM on the site I mentioned a plug and play, or is the ad intentionally misleading?