Need some with O2 sensor problem.
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Joined: Jun 2013
Posts: 3
From: Port Hueneme, California
Need some with O2 sensor problem.
Hey guys new to the forum and being on any forum in general honestly so forgive me for any flubs. I recently bought an 04 S4 with the 4.2L w/120K. Love the car it runs like a beast and it’s a great car. I'm having an issue with an O2 sensor that has me a little stuck. The story goes like this:
I bought this car in the high desert of California where I'm originally from, very hot and dry climate. No problems when I checked it out, no CEL's nothing, its clean. Drive it home to Port Hueneme which is a beach community. The next day CEL, P0431 is the code and I notice its running rich with a considerable gas smell. Did a little tune up, air filter, new Denso plugs, checked all the coils, cleaned the MAF, and aligned the throttle body. Gas smell is reduced to what I would think is acceptable for a V8, not sure how these normally smell but there’s a little gas smell but nothing that concerns me. I cleared the code took it out again, it comes back right away.
So to determine whether it’s the O2 sensor or the cat I swapped the downstream O2 sensors with each other and took it out again. CEL comes back this time it’s P0421, so obviously its O2 sensor not the cat right? I drove it back to the high desert this weekend to visit some family, on the way out of town I stop to fill it up and clear the code because it annoys me. As soon as you get out of the Canajo valley where I live the temp picks up dramatically, usually about 20 degrees hotter 10 miles down the road. The CEL never comes back on! 2 days in the hot dry desert and this things running like a champ just like the day I bought it no lights no problems. I drive it on short stop and goes, longer trips, couple WOT runs everything is good and I'm happy happy happy.
I drove home yesterday with no problems back to the beach. Wake up this morning and run some errands, CEL pops back on, P0421
Any ideas why this O2 sensor would work in the hot dry desert but fail in the cool slighlty more humid beach environment? Is it a fuel trim issue or is the O2sensor just bad but works fine when the air is dry??? I'm out of ideas and could really use some help. Thanks!
I bought this car in the high desert of California where I'm originally from, very hot and dry climate. No problems when I checked it out, no CEL's nothing, its clean. Drive it home to Port Hueneme which is a beach community. The next day CEL, P0431 is the code and I notice its running rich with a considerable gas smell. Did a little tune up, air filter, new Denso plugs, checked all the coils, cleaned the MAF, and aligned the throttle body. Gas smell is reduced to what I would think is acceptable for a V8, not sure how these normally smell but there’s a little gas smell but nothing that concerns me. I cleared the code took it out again, it comes back right away.
So to determine whether it’s the O2 sensor or the cat I swapped the downstream O2 sensors with each other and took it out again. CEL comes back this time it’s P0421, so obviously its O2 sensor not the cat right? I drove it back to the high desert this weekend to visit some family, on the way out of town I stop to fill it up and clear the code because it annoys me. As soon as you get out of the Canajo valley where I live the temp picks up dramatically, usually about 20 degrees hotter 10 miles down the road. The CEL never comes back on! 2 days in the hot dry desert and this things running like a champ just like the day I bought it no lights no problems. I drive it on short stop and goes, longer trips, couple WOT runs everything is good and I'm happy happy happy.
I drove home yesterday with no problems back to the beach. Wake up this morning and run some errands, CEL pops back on, P0421
Any ideas why this O2 sensor would work in the hot dry desert but fail in the cool slighlty more humid beach environment? Is it a fuel trim issue or is the O2sensor just bad but works fine when the air is dry??? I'm out of ideas and could really use some help. Thanks!
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