Someone please please please help! So my check engine light is on which means I can't get my car to pas smog. I brought it to the mechanic shop my dad goes to which is not strictly a Volvo shop and he read the code p0133 which I believe was the oxygen sensor. He then went ahead and replaced it. The next day, my check engine light came back on! I took it back to the shop and they read a code for p0420 set for the catalytic converter. They found the hfm sensor reading marginal. Cleaned the hfm sensor and cleared the codes. Well.... Check engine light came back on! I brought the car to another mechanic to get a second opinion and he read the code for the o2 sensor that was supposibly just changed. He did not get a convearter code. This has been such a hassle because in the midst of this, I was 8 months pregnant. My daughter is now two months old and the problem has not been fixed. So... I went and got a third opinion, this time from an independent Volvo mechanic. He used a Bluetooth diagnostic scanner and came up with these codes ... ECM-16 and ECM-A1. He did not come up with a catalytic converter code. He said the emc16 code required a cable adapter which is to be hooked up to the o2 sensor which he noticed my car did not have. He then said the other code read for the engine coolant temp sensor but there is still no guarantee this will get rid of the check engine and allow my car to pass smog. I contacted the very first mechanic shop I paid money at to get a new sensor and let him know I got a second opinion and I got a code emc16 for a weak front o2 sensor which requires that cable/adapter I do not have. I brought it back to them to check it out and they say they get no emc16 code but it was for that po133 which they're not reading low. Please can someone help me figure out what might be going on and why these two shops are getting different codes for the same front o2 sensor?

 

I had this same issue with my car. Even after replacing the O2 sensor and adding the adapter cable to the O2 sensor harness, P0133 would come back.
The only fix for me was to go to a Volvo dealer and have the ECM updated. It was around $300 but it fixed the issue.

 

Will Volvo be able to provide me the harness free of cost? Did you install it yourself ?

 

The cat convertor below efficiency code can be eliminated with this:
Oxygen Sensor Spacer (CEL Boss)

It's only good for the bottom O2 sensor, not the top one. The top one needs the adapter harness and the software update.

 

Thanks for your response. Would you happen to know if I need to change the engine coolant temperature sensor as well for it to pass smog or by taking care of the harness and software update will solve this issue?!

 

In my experience with my 2001 the fault code for the coolant temp sensor was fixed with a new sensor. These are available at the local parts store but very expensive at $50+. However, they are available online at RockAuto for $7.51 + shipping.

RockAuto Parts Catalog
ÜRO PARTS Part # 9125463

Now there is another code regarding the cooling system where the problem is a bad thermostat. Easily and quickly fixed with a new t-stat.

When I bought my 2001 from the local stealership they programmed the ECM and fixed the O2 harness as part of my purchase. Check online to see if this is a recall item. A faulty emission system from the dealer cannot be legal.

 

Information removed.

 

I bought the adapter harness for the o2 sensor from the dealer. I paid ~$50 for it and installed it myself. It's not too hard, all you have to do is plug the upstream O2 sensor into the adapter and then the adapter into where the upstream O2 sensor was unplugged from.

My car also had the P0420 cat code. I fixed mine just like how Hudini suggested to with the O2 sensor simulator and P0420 never came back.

I replaced my coolant temp sensor and thermostat together and that fixed the problem for the codes I was getting for them as well.

 

You must work for a dealer. Charging money to fix a factory flaw pisses me off and reinforces the thief mentality associated with all dealers, new and used.

And your assumption of the bad cat is flat wrong. Only a smog test can check a cat, not a 2nd O2 sensor coupled with poorly written software. Personally, if my cat convertor ever fails to provide the federally mandated emissions conversion then I will find a different car to drive. And just for the record, my car hasn't had a check engine light for the cat below efficiency since installing the product mentioned above.

 

I do work for a dealer and I see customers all the time who think that common repairs must be free, especially when they read the misinformation posted all over message boards like this. I have had to tell many customers that just because someone on a message board says there is a recall or should be a recall for their problem, it does not mean there IS a recall. The car is out of warranty. The manufacturer is required to repair problems that occur when the car is in warranty. If an ECT sensor fails 12 years after the car was made, they are supposed to replace it for free just because it is common? I don't think so.

That's great that the O2 spacer worked for you. But I was just commenting because of your assumption that it is illegal to sell the car with a bad cat. It is illegal to tamper with the emissions system and I'm almost certainly that spacer would qualify. It doesn't change the efficiency of the cat at all. The cat has an 8 year 80,000 mile warranty. You think manufacturers should seriously have to warranty it for longer?

 

I had the adapter cable installed, and coolant temp sensor changed, as well as thermostat and my check engine light is STILL on!! I got another reading and code ECM 28 came up which I believe is faulty front oxygen sensor. When I had originally taken it to the shop where I had the o2 sensor replaced, they said they tested it and read its working within the parameters.
This part is under warranty. I'm wondering now what do I do? Didn't I just pay for a new sensor that now 3 shops have said its faulty?? Please help

 

The only way I got the code to go away and stay away is by going to the dealer and having the ECM updated. It went away completely after that. I replaced the o2 sensors (both) countless times to get it to go away but it never did. The adapter cable made the code stay away for a day or two but it came back after that. I bet if I just did the software update I would have never had to replace the o2 sensor in the first place.

 

[QUOTE=davidx1994;341873]The only way I got the code to go away and stay away is by going to the dealer and having the ECM updated. It went away completely after that. I replaced the o2 sensors (both) countless times to get it to go away but it never did. The adapter cable made the code stay away for a day or two but it came back after that. I bet if I just did the software update I would have never had to replace the o2 sensor in the first place.[/QUOTE


What exactly is the software update? Is it when they clear the codes? Can an independent Volvo mechanic do this for me? How do I describe this update ?

 

No, a software update is when you have the software on the ECM upgraded.
Clearing codes is just that, clearing codes. The software update addresses the bug where the ECM sets out the trouble code that the o2 sensor is responding too slowly.

I cannot find the information right now but when I had the problem, I read somewhere that with the old software the car looks for the signal from the O2 sensor too quickly, so they released the new software and adapter cable to fix the problem.

I'm not sure if an independent mechanic can do it. I had it done at a Volvo dealership (Gengras Volvo Meriden CT). I would just ask them if they are able to do ECM updates.