4-3-5 heated oxygen sensor - slow response

camper guy · Post by **camper guy** » 28 Jan 2004, 09:01

I've had to clear this code twice in the last 2 months, both times it's been very cold out. Is it faulty or is it the extreme temps? Negative numbers.

Post by **matthew1** » 28 Jan 2004, 11:09

My Guess: if the code came back twice, it's probly a combination of the sensor going out and the cold. You're going to have to replace that sensor one day

. And you can look forward to a little better milage when that day comes.

camper guy · Post by **camper guy** » 28 Jan 2004, 16:28

How much better mileage? I'm getting about 23 mpg average now.

When it does go, does it stop the car or can I wait another 5K until I put it in for the timing belt replacement, assuming the light doesn't come on and stay on.

Post by **matthew1** » 28 Jan 2004, 23:44

Your milage will continue to degrade. You can also count on making life harder on the other O2 sensor since the emissions leaving your engine could be richer.

Also the engine overall can suffer because the loop is not closed in the fuel/air --> combusting --> monitor cycle.

And, if that's not enough, your pollution will increase.

FWIW, my milage went down to almost 16, then up to 19 when I got the new O2 sensor. Do it yourself... it's really really easy. Easier than changing oil. The hardest part is paying for the sensor.

camper guy · Post by **camper guy** » 29 Jan 2004, 17:59

Easier than changing oil? Really? I've done the oil and the thermostat.

Post by **matthew1** » 29 Jan 2004, 19:14

Yes. Drive up ramps, unscrew old sensor from exhaust, follow back (up into the engine bay) and unclip wire harness, screw new sensor in, attach wire harness.

The harness is tough because it's in a place good only for small hands. But it's not difficult, just tricky.

If the sensor is stubborn coming out, shoot some WD40 on it. Hell, do that anyway.

Post by **matthew1** » 29 Jan 2004, 21:38

I shouldn't say screw in, but rather 'wrench in' because a wrench is what you'll need. Open-end. 19mm I believe.

camper guy · Post by **camper guy** » 30 Jan 2004, 12:58

Sounds easy I guess. Now how do we know it's the front sensor and not the back? Because of the code? Also I've called a few places for prices, NAPA can't get it, it's on back order at $194.95, Pepboys is $180, same thing and Volvo wants $207.

I saw it on the IPD site for $175 plus shipping. Any other places to buy one or just go with the Bosch one from IPD?

Post by **matthew1** » 30 Jan 2004, 14:01

I don't know which one it is from that code. Perhaps someone here will know, or else IPD.

I'd go with the IPD Bosch one, unless you want to mess with universal ones -- you have to figure out the wiring and maybe splice the connector onto them. There was talk of success with that method perhaps even here on MVS -- can't remember where I saw it. They guy saved a bundle by buying the universal sensor.

camper guy · Post by **camper guy** » 30 Jan 2004, 16:46

I'm having my regular guy fix an exhaust leak on Monday, Can't get the clamp to move, he can probably weld it. I just read on Volvospeed that an exhaust leak can lead to a faulty read. Maybe that's it? I'll have him check it out before I buy a sensor.