2001 V40 -Replaced Oxygen sensor, check engine light back

Billbrink · Post by **Billbrink** » 10 Jan 2008, 06:28

-A day later.
I had been driving for a couple months with, presumably, a bad O2 sensor (the front one -according to the code generated, was responding slowly).
So I replaced it with an OEM Bosch, and took it by a local Volvo specialist to check the readings and reset. When we hooked it up to the rather elaborate and official Volvo diagnostic system, it showed the sensor functioning exactly as it should.

Now, one day later, the check engine light is back, and I have no doubt what the code will be.

So here's the question: What could cause this?
-Problems with the rear O2 sensor? The mixture controls?

The car is running fine, and only has 82K miles on it. I'm a reasonably adept mechanic, but this is a nightmare.

Has anyone experienced this, or know a guru?
Thanks in advance.

Post by **MadeInJapan** » 10 Jan 2008, 16:04

Don't assume it's the 02 sensor again. When things were going on my car, they were happening in series. Anyway, get your codes read. If the 02 sensor shows as the culprit again, check other things that might cause the 02 to respond in this way such as vacuum leaks or dirty MAF sensor....

Billbrink · Post by **Billbrink** » 10 Jan 2008, 18:52

Well, the code was 1033 I think (stage 1 slow to respond..."); It was the same code I have gotten on 3 different sensors over the course of 1 week. And each time, the check engine light came on as soon as I had completed the initialization cycle.

I talked to one of the techs at a local dealership, and was told much the same as you. He also said that a bad after-cat O2 sensor could cause similar problems. That will be stage one. It's expensive, but relatively cheap compared to MAF sensor work.

No vacuum leaks: that's a different animal. The one suspect is the line which connects the intake manifold to the brake booster. The fitting at the manifold end is relatively loose, (and I was mortified by the design the tube simply slides into a hole in the manifold, with a hard plastic sleeve around it. Not so much as an O-ring!) -BUT I hear no hiss, so I sprayed a little wd40 on it It was drawn in, but not with any real force. I may be reduced to using a little tape to tighten things up.

So, the rear sensor goes in tomorrow, and I'll let you know what happens.
-Bill

Billbrink · Post by **Billbrink** » 13 Jan 2008, 23:43

OK, the replacement rear O2 sensor was installed 2 days ago. At this point I have driven the cycle, and the check engine light has not come on.

SOMETHING TO REMEMBER:
Apparently a bad rear sensor can make the OBD think the front one is bad.
For those of you who are taking notes; The code I kept getting was:
"P0133: O2 Sensor Circuit Slow Response (Bank 1 Sensor 1)".

I'm left wondering whether I even needed to replace the front one. Figuring that out up front would be nice, but even with the Volvo diagnostic system plugged in, it's very hard to tell.

I've been told most repair shops will automatically take the "shotgun" approach, and replace both sensors. That's a lot easier for them and a whole lot more expensive for you. I got my OEM sensors at Advance Auto parts for less than $150 each; which is expensive, but a bargain compared to what a dealer or mechanic will charge you.

So there you go. A lesson learned.
Bill

Oh Yeah. One more thing.
If you are thinking about changing these sensors out yourself, DO NOT USE A STANDARD O2 SENSOR SOCKET WRENCH! They aren't deep enough for the Bosch units, and you run a very good chance of damaging the sensor. Get one which has the ratchet connection offset to the side.

PetiteElizabet · Post by **PetiteElizabet** » 16 Jan 2008, 08:03

Hey all -

I have a 2001 Volvo S40 and I was recently told that my oxygen sensors were needing to be replaced (i got the report that BOTH should be replaced now I'm not really sure if that's the best route to go). I noticed that someone mentioned getting the parts for less that $170 dollars. I found a site that sells "universal" oxygen sensors for 2000-2004 Volvo S40s for about 75$. I was wondering if anyone new about the quality or how much I could trust buying those and using those in my car. I was thinking I would buy the parts and then bring the parts to the mechanic's shop and ask them to install them. Any suggestions or feedback is greatly appreciated! Thanks

Enjoy your week.

Post by **MadeInJapan** » 16 Jan 2008, 14:45

You never mention your mileage. Usually these start to go after 100K miles. 850 and 70 series owners have not had good luck with universal sensors...don't know about the 40 series but I would assume the same.

PetiteElizabet · Post by **PetiteElizabet** » 16 Jan 2008, 14:59

My milages is actually just over 60,000. But the car's been driven a lot i bought it used and it was just over 32,000 miles at that point. It's been a lot of highway usage driving btw jersey and ny and ct. on a farily regular bases (ie LOTS of traffic jams). have no idea if this would affect it. I Recently had to replce the Oring as well in the engine because it cracked and all the fluid leaked out.
Thanks! Anymore feedback would be great!

Post by **MadeInJapan** » 16 Jan 2008, 19:39

Wow...an o-ring in the engine. Really, at those miles I'm really surprised that you're looking at 02 sensors. Certainly make sure it's not vacuum leaks or a dirty MAF sensor first....very rare that 02's go before 100K miles.

whiteskies · Post by **whiteskies** » 28 Oct 2013, 11:08

I just want to say Thank you to billbrink for posting this, as I have a 12 year old 2.0l auto v40, engine light keeps coming on with the P0133 error and no one, including Volvo UK can tell me the issue. So i am going to order both sensors in and replace them, the car only has 129k miles and for the past couple of years with this light coming on the fuel consumption has gone through the roof, hoping this may sort the fuel issue too.

goodboy · Post by **goodboy** » 26 Mar 2014, 05:58

I Recently had to replce the Oring as well in the engine because it cracked and all the fluid leaked out.

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