Hello everyone. This is my first post, but I have been searching and using this forum for about a year now, and I want to thank everyone for the helpful information.

BUT...

'01 S40 86,000 miles. CEL is constantly on and reads P0133 - O2 sensor slow B1S1. I have replaced it first with the bosch universal, but the code came back. Then I used the Bosch OEM sensor, but it came back. I have erased the code multiple times, and it won't go away. Also, I have intermittent misfire (different cylinders), but it hasn't happened in over a month. I just got a *ticket* for past-due registration, and have to get the CEL off to pass emissions so I can register. Please help. What is the next thing I should try? I am putting in new spark plugs and will clean the throttle body. Could this help? Any info would be helpful. Thanks.

 

There are two O2 sensors. Try replacing the bottom one with the generic Bosch sensor you first purchased. Or try switching them, bottom for top. Not sure if the connections are the same so that might not work.

Did your car have the O2 wiring harness adapter? It looks like an extra harness added between the original O2 harness and the cars connector. If you trace the wires it looks like this extra harness reverses a couple wires.

When my 2001 developed a miss it turned out to be the coils. I ended up replacing both coils and both plug wires plus all 4 plugs. If you replace the coils, check out Autozone. They had new Volvo coils in a box marked Duralast which is Autozone's brand. $45 per coil. When I bought mine I opened the box and out popped genuine Volvo coils. I bought my wires from IPD. Plugs were the NGK Iridium from Advance Auto.

 

Thanks. I already returned the universal O2 sensor for the OEM one. I do not think I can switch the pre and post O2, since I suspect they are different (someone tell me if I'm wrong)and I haven't got a B1S2 error code. I do have the harness adapter, but the wires do NOT seem to reverse. The wires of the O2 sensor are in the exact same order as the adapter. Thanks for the info on the coils and plug wires, as I will be changing those soon. But my main concern right now is will replacing the plugs/wires/coils do anything to get rid of the P0133 code?

 

IIRC, only 1 wire changed from one side to the other. Not sure why. I think it was the white with orange wire. Oh well, doesn't matter as long as it's there.

Narrow Band O2 sensors all act the same, the difference being heated/unheated, number of wires and the connection. You would think Volvo would put the exact same sensor both before and after the cat, but only one way to find out for sure.

 

OK> I still need help...and quickly so I can get my emissions done by the end of the month. I took my s40 to an indy mech with the volvo computer diagnostic and it came up with.

CCM-0052 Left-hand seat heater. Faulty signal. Permanent
CCM-0053 Right-hand seat heater. Faulty signal. Intermittent
CEM 0027 Battery voltage. Signal too low. Intermittent.
ECM-28 Front heated oxygen sensor (HO2S) short-term
ECM-9A Communication problems, Immobilizer

The mechanic said the low voltage might cause codes to keep popping up, so he replaced the battery (it was the original -7 years old) with an interstate battery. He alsosaid the wiring harness adapter (front O2)was unneeded, and took it out. Well the CEL light for the front O2 sensor came back that same day. I put the harness adapter back in, reset the lightand the code came back AGAIN. TECH said something in another thread about resetting the computer adaptives. I'm not sure if that's ever been done since I replaced the sensor by myself. How do I do that? And please someone tell me what else I should look at to try and get this damn light to stay off. I'm getting desperate.

edit: I have also changed the spark plugs and cleaned the throttle body. The ride is smooth and like new, but the code is too stubborn. Suggestions?

 

Are you 100% sure there is no Vaccum leaks?
A vaccum leak can cause the code.
Also did the shop watch the voltage to see if the sensor is working?
Did the adapter harness come from Volvo?
The adaptives need to be reset through Volvo's system.

 

Tech, Thank you very much for chiming in. You have helped hundreds of people and saved them thousands of dollars, I'm sure. I appreciate you taking time to help me.

I am not 100% sure of no vacuum leaks. I did the carb cleaner spray test around the throttle body and turbo. No surges or sputtering. Is there anywhere else to check for leaks (ora better method)? The shop said they checked connections and the sensor was working (did not specicfically say they checked voltage, though). The harness was on the car when I bought it 18 months ago. It does not say volvo or have a manufacturer on it anywhere, but the wires are numbered on the plastic plug 1-4 and the wires match exactly with the O2 sensor. Also, I have been driving for over a month with the new sensor. Do the adaptives reset themselves, or should I just take it to the dealer to have them do it? Thanks again.

 

This seems to be a problem that some S40 owners get after awhile, and no one can adequately answer why. I have a problem with mine that sounds a good bit like yours, although I don't have the other issues you list (low voltage, heaters, etc.) My check engine light has locked in and keeps coming back with the same O2 sensor code, even though I have had that replaced.

I've asked my Volvo dealer about this, and the next step they told me was to have an emissions test ran. Volvo dealers will do one for around $85, but I called around and Maxi does the same check for $40. So I went to Maxi and:

1) Pressure check - no leaks
2) Spark plug check - all good
3) Sensor check - sensors changing voltage level in spec

Maxi ended up not even charging me for the check, since they couldnt' find anything wrong. They did tell me that they could not check the turbo, and that I might want to have that checked out as well in case that could be doing something to cause this. I haven't done that yet.

The only other thing that I can think of is that the computer itself (or I should say the programming for this code) has some kind of problem that too easily triggers this code.

MY QUESTION: Has there been any programming updates for 2001 S40's over the past few years that might affect this particular reading, and if so, when was it?

 

When I first bought my 2001 about 4 years ago, the dealer reflashed my ECM. Not sure why but it was done at no charge to me. Recall maybe?

 

You might want to have the Dealer reset them.
You might also want them to recheck the other shops work.
I hate to tell you to spend more money but sometimes the Dealer is the best route.

 

Thanks Tech...I just had the dealership reset the adaptions - only $60 - and they said it should fix the problem. I have only 1 day to get an emissions test so I will have to go through the 17step drive cycle to get the computers to "ready status". I read here somewhere though, that you only have to drive on the highway without touching the brakes to set them to "ready". Anybody have any input onthe best (and quickest) way to get the car ready for emissions?

 

Sorry no easy way I know of.
Hope all is well let us know how you make out.

 

Well...good news. The adaptions reset got rid of the CEL, and I was able to pass emissions. I didn't even have to do a drive cycle, per se. I just drove fora day and a half- mostly city and then a bit of highway. All systems reported as ready. Thanks again, TECH, for the help. And to anyone else out there who replaces your own oxygen sensor - GET THE ADAPTIVES RESET AT THE DEALER! If I had known that in the beginning, I would have saved myself a little money, a lot of time, and whole hell of a lot of aggravation.