Hi guys, the other night I drove 5 miles to a store. When I came out and restarted her, check engine & restricted performance message came on!

After 2 restarts restricted performance went away, check engine was on. Next day I got the reader to work, saw P0141 & (from memory) P0144 codes.

I couldn't find p0144, so I question my memory. P0141 seems to point to the heated O2 sensor left bank. Now the OBDII reader said the p0144 was same thing right bank but we all know how accurate they are.

Well at 142,000 miles, I figure its time to replace the O2 Sensors. I just looked, its not obvious. Are there 2 sensors per side?

Anyone remember where they are located?

While we are on the topic - prices are all over the place! Denso from jaguar is >$330, parts geek has replacements from around $35 each. Have you had positive experiences with rather cheaper ones?

FWIW, 2 days + 50 miles later no check engine light.

Thanks guys, John

 

I understand there is an access hole under the footwell carpet to access the lower one.

 

Stick with genuine Denso oxygen sensors. I can usually find them on amazon.com for around $100 each. The cheap knock-offs are not worth the risk....

 

Johnken,
Although I did replace mine Summer 2019 with a Bosch, I agree with Jon (and probably most of the forum) that Denso is the way to go. Since then, I have replaced 2 sensors on another make vehicle with Denso's. and have had excellent results.
As far as installation goes, I opt to go with dropping the catalytic converter (I think that was Graham's recommendation). The manifold studs required a good soaking of penetrate and I still managed to pop one stud which I did have to then extract the bit and replace. Regardless, if I have to do it again, I plan to drop the cat.
Also, to gain access to the O2 connectors, with proper support and padding, I lay on my belly atop the engine, which affords me use of both hands. (your results may vary)

 

The oxygen sensor electrical connectors (mounted on the firewall) are indeed a bitch to get to. As hard as I tried, my monster hands never could get down to them. My small-handed neighbor saved the day on that job, but even he had a tough time with them. Persistence finally paid off....

 

I've had success easily replacing the downstream sensors from up top.

Once I confirmed the sensor was bad (CEL and obd codes were enough for me) I was simply willing to destroy the sensor in situ. Meaning I would disconnect the battery (good time to do hard reset while doing the work), snip the wires to the O2 sensor in question, rip off the top of the sensor (13mm wrench - round end over the shaft and give a good twist) essentially leaving the O2 sensor 'bolt' on the cat, take a 6pt 7/8ths (I think it is) socket and a breaker bar (if needed) and spin it out. Mine didn't require a breaker bar. No deep socket needed.

I soaked the head of the O2 sensor first for good measure. It came right out. Didn't feel too bad about destroying the sensor as it was dead anyways AND, temporarily (if need be) the car defaults to factory sets (I think) with O2 sensors unplugged IF limited driving is needed, anyways... No big deal, the sensor bolt came out easy. All and all a 20min job.

On my car there was/is a slight recess around the base of the O2 sensor that is built into the design of the CAT so a really meaty socket will have a tough time making it's way DOWN to fully seat. Just be careful.