Hello Again!

My 2005 Volvo S40 2.4i just threw a P0101. I understand what may cause this code, that's not why I'm writing.

My question is:

It sounds like there may be a vacuum leak near the firewall of the car. What's weird is it sounds like the leak cycles on and off. So I guess my question is what part may be connected to a vacuum line and cycle on and off during an idle? I used carb cleaner to try and find a leak, but never heard any difference on hoses/intake/etc...

Other symptoms:

During idle, the RPM's fluctuate about +- 50RPM (it doesn't register on the tach, can hear it by sound very clearly though).

This fluctuation ONLY happens when the vacuum leak sound goes AWAY. When the vacuum leak sound cycle's on, the idle is very consistant.


Any ideas experts?

Thanks for any input whatsoever

 

Allow me to clarify... I'm not saying there is a vacuum leak, but i hear what sounds like a vacuum leak. It very well may be a normal sound coming from a normal piece of equipment...

Is there a part that goes sounds like "click....click....click....click...." but replace "click" with the sound a leak would make... and also cycle on and off, near the firewall?

 

.......

 

Does anyone at least have a link to a vacuum diagram for a 2005 volvo s40 so i can try and figure it out?

 

I'm only posting to help someone who may have the same problem as me in the future.


I think I found the vacuum leak underneath what I'm assuming is the evap. canister.... It's immediately to the right of the intake, and it looks as though a metal vacuum tube transitions into a rubber tube, and somewhere around there is the leak. It's a tight fit so I need to take everything apart during the weekend to do a good check.

Can someone please, pleasee just tell me if I'm right on assuming the part I'm describing is the evap canister? I'm pretty sure it's the only place where a metal vacuum tube changes over to a rubber one to go into this part. The metal vacuum tube runs behind the intake, and goes back towards the firewall to go to this part.

 

Okay it's not the purge valve, it's the DM-TL pump (leak detection pump). When this cycles ON to test the system, the engine idles fine... when pump shut's off, that is when the RPM's begin to fluctuate.

Come on now, this is a challenge for you experts. Where would I have a vacuum leak only when the DM-TL pump is off?

 

I've got a 2001 V40. I occasionally get a CEL that pointed to P0101. I tried to get help on this forum with no luck.

Someone suggested that it might be a vacuum leak but any attempt on my part to isolate a leak failed to find one. I never heard the leak sound you describe.

The other suspect was the Mass Flow Sensor. I tried cleaning the MAF and the CEL occurred less frequently but still pretty often. I replaced the MAF with an OEM part and I thought this cured the problem. I still get the CEL on occasion but only about 10% of the time now. I have never been able to solve the problem. The MAF is really easy to replace.

The only driveability problem is that sometimes it seems that the acceleration isn't as strong. I don't know if the CEL & acceleration problem are related.

Wish I could help you more. Good luck.

 

I appreciate you getting back to me.

I tried replacing the MAF with no luck too. I'm almost certain it's a vacuum leak somewhere, there is a slight rough idle, but only when the leak detection pump is off. I'm wondering if the pump is leaking vacuum when its off... however it's a $300 part and I'm not about to take a guess.


If I figure it out I'll be sure to post my results back.... a lot of people say that but nobody does, which doesn't help you and me!

 

I have the same sound its like a click click click in time but it some times stops its not always the same rhythm i get codes p0243 and p0101 i was about to check the mass airflow and clean the Idle Air Control valve I started checking hoses in other areas because my engine isn't running well at all now. It runs a little and then cuts off. I was wondering if you found out what the sound was near your firewall? because it sounds like its same issue or sound that's coming from my ENG and what was the cause of your problem?

Thanks

 

The sound that I was referring to in my earlier posts, I believe is the DM-TL pump (leak detection pump). Its a little diaphram vacuum pump that pulls a vacuum on the fuel system to test for leaks. The sound that I'm referring to is normal.... I cannot say the same for you because I don't know what it sounds like!

Unfortunately it is not my vacuum leak problem, which I still have yet to find. When I find the time I'm going to look one more time for a vacuum leak using a propane tank and hose.

Please let me know if you find anything. Good luck

 

Update on my P0101: A friend at work had a code reader that can also reset codes. He read the code & reset it. That was 2 months and about 1000 miles ago. I haven't seen the CEL since.

 

Bringing this back from the dead. New symptoms, same problem.


So to quickly reiterate, on my 2005 Volvo s40 non-turbo, I was getting P0101, P0172. No signs of vacuum leaks, changed MAF, changed O2 (needed them anyway), same problem.

I recently had a smoke test done, still no vacuum leaks.
I tried another MAF (used, not reman.), still same problem

Symptom? - With the key on but without engine running, the IACV is very noisy. It has a constant high pitched buzz, and sounds like a computer hard drive going crazy. I'm assuming it is opening and closing rapidly? Again engine is not running a this time. IACV seems to be functioning normally otherwise.

Also a new code I'm getting is P0026, which I've come to find out is pretty much useless to me.

Any help?

Thanks guys.





As a side note for people who get the wet back floor. I used a compressor to blow out the sunroof drain lines, and it didnt' fix the problem. Long story short the drain line became disconnected on the drivers side, by the bottom of the windshield behind the decorative cover thing (interior). Hope this helps someone.

 

Well I believe my saga is finally over (knock on wood).

This weekend I did the following, and so far my CEL has remained off:

1. Replaced MAF Again with a used one on ebay for $35
2. Replaced spark plugs which were long overdue
3. Cleaned throttle body while it was off for spark plug change


Now after I replaced the MAF, the p0101 code was gone but the P0172 remained. After lots of googling (if thats a word) I learned my OBDII scanner erases codes, but does not reset fuel trims. The P0172 was actually a long term fuel trim code, so when I put the new MAF in, it was still using old fuel trims and throwing the code. I reset the ECM by disconnecting the battery for a while, put everything back together and went driving. It took a while for all readiness monitors to be ready, but once they did no codes came back.

The P0101 was most definitely from the aftermarket MAF that I originally put in, and when i originally put in the OEM MAF from the junkie, I didn't know about resetting the ECM.

Anyway, I'm posting this to hopefully help someone in the future. Good luck, this code is a killer.


Oh and the p0026 was the camshaft reset valve. $120 new from volvo, on my car (2005 volvo s40 2.4i non-turbo) it is under the timing belt cover, a 1" cylindrical part held on by a single torx screw. The other cylindrical part next to it is just a plug for if they were to put in an exhaust ccvt (for turbo cars I beilieve?). That is why there is no electrical connection on that one.

 

I'm having problems with my mass air flow. I have replaced twice with remans and still getting code P0101. The car acts like its going to stall out when its at idle. Any ideas would be appreciated. I have also recently replace the air filter and the cabin air filter. Should I get an original maf from volvo or what? I have a 2006 Volvo XC90 with 72,000 miles on it.

 

Drop the aftermarket MAF and buy a genuine OEM. Like I said in my previous post, I bought a used one on ebay for like $35. Its worth the money to have an OEM.... and for $35 you can't go wrong. I struggled for a year because i refused to believe an aftermarket MAF was the culprit. If it doesn't say Denso or Volvo, you're just asking for more aggrevation.

 

Ok thanks for the advice...I will find one and see if that works. I did get a new code today P0170 Fuel Trim Bank 1. Do you have any idea what that is about. I almost think I may have a leak somewhere. I will try the new MAF first then go from there.

 

As stated above, the fuel trim code is related to your MAF problem. Replace the MAF, disconnect the battery to reset the fuel trim, then erase the trouble codes with a code reader. At least that's how I understood it.

 

Yeah but just to clarify there are long term and short term fuel trim codes. Not sure which you have. The long trim code is related to a bad maf. Short from what I've heard can be a vacuum leak or failing o2 sensor. Those are maintenence parts so may as well replace them if they're original. But first do what I said and get an oem maf, then reset fuel trims by disconnecting the batt for a half hour.

Keep us informed. I know how frustrating this code is so I'm happy to give my input after a year of troubleshooting.

 

Ok I have finally replaced the MAF Sensor again with an original part this time that I got on ebay. I disconnected the battery when I did this and put everything back together and the code did not go off and the car still acted like it wanted to die. I am so frustrated, if I had any money I would sell the thing and get something completely different but I'm stuck with it!!! There must be a leak in hose I'm not sure how to check that..... I guess I will take it to a mechanic and have them look at it and pray that is doesn't cost me an arm and a leg!!! Maybe I can replace the O2 sensors I saw those on ebay as well. Any suggestions?

Thanks!!

 

Do you have a code reader? Erase the code and then disconnect the battery for 20+minutes. This should reset the fuel trims. I have a hunch you didn't leave it disconnected long enough.

Depending on how many miles your car has, you may as well replace the O2 sensors since they are a maintenance item. Again and I can't stress this enough, only use DIRECT FIT BOSCH/DENSO or Genuine Volvo sensors. You will regret putting in a universal sensor. Go to the Bosch website to find the correct sensor then put the # into Amazon. They have great prices.

Not sure what year your car is, but give your vin # to the dealer service department and see if there are any recalls. Mine had a fuel pump recall (plus the breather box)

A vacuum leak is the most annoying thing to diagnose, but not impossible. People suggest using propane around all your vacuum lines and listen for changes in RPM. This can be pretty dangerous and not suggested by me... I had a shop smoke-test mine when I thought I had a vacuum leak. It only cost me $25 but in my mind eliminated a big "what if". Other shops wanted to charge me an hour's labor.

Finally, and actually probably should be one of the first things you try next, is to have a volvo service shop hook up your car to their OBDII. There are many things your handheld reader can't pick up on that a $10,000 volvo scan tool will. Again, I was charged about $50, but it is what eventually lead to me fixing all my problems.

Good luck, and report back. It helps other people who will inevitably have the same problems as you and I.