Ok I did what you said and disconnected the battery for 30+ minutes and it seemed to work perfectly. I thought I was in the clear, however today i just filled the tank up with gas and after 7 miles or so it started idling rough again as if it was going to die and in-fact it did. So when I got home I disconnected the battery again for 30+ minutes and now seems to be fine. My car is a 2006 xc90 with 73,000 miles. It is due for regular maintenance at 75,000 miles so i will replace the o2 sensors then and I guess have them check for leaks. Are the 02 sensors easy to replace? If so I will do those myself. Any ideas what the correlation between filling up and the rough idle could be?

 

When it died any new codes? It could take a week or more for a code to trip again depending on how long it takes you to finish a drive cycle. You really shouldn't keep disconnecting the battery unless necessary, I only mentioned it the first time to reset your fuel trims.

The front (pre-cat) o2 sensor is easy... you do need to pickup a $5 O2 socket or you risk damaging the wires. Id give it a shot yourself first, its much cheaper. And honestly you only need to replace the pre-cat O2... as long as your cat is still in good working condition, the post cat sensor should be ok.

Before you bring it anywhere just give all the vacuum lines a good check.

 

hey guys. 98 s70 glt 2.4l lpt. p0101 code, also browsing this ever so increasingly popular topic. car is having the same issues, originally a p0108 (bad maf, replaced from junkyard as well as air filter) seemed to alleviate the problems, then the dreaded p0101. initially went searching for leaks, found my intake hose had popped itself off of the filter box. no biggie. well that fix worked for a week. car ran great. than, symptoms came back, acts up well after the car is warm, or on hotter afternoons, the car can either be fine or acting up. acting up being an occasional high idle; 1100 instead of ~850, and downshifting into 3rd upon releasing gas pedal and slipping immediately back into 4th. (checked throttle housing, seems fine, sprayed carb cleaner in most vacuum hose areas i could find, going to try cleaning the maf even though code is different, and also going to order another one from ebay.) thinking i haven't found the leak yet, its another sensor or a turbo leak, maybe bad ecu that learned something it shouldnt? ANYONE WITH INSIGHT, PLEASE... i have a trip coming up and really dont want to take my baby in this kind of condition. i"ve owned it for 6 years now and should be running in the "like new" condition it did at 94k the day i got her.
thanks much to anyone with a specific area to look at, with a p0101 it couldn't be tranny problems...

 

hey what kind of characteristics would be present if its a long term / short term fuel trim code? i have p0170 on my 2005 s40 2.4i - the check engine light comes and goes. between starts. the only symptom i have is heavy fuel consumption!

 

Hello all. My 2003 S40 is throwing off a mass air flow sensor code (P0101) and Bank 1 too rich (P0172). So far i have already cleared the cleaned the idle control valve and mass airflow sensor, put in new 4 sparkplugs, and a one new coil. i already cleaned the sensor but the code reappeared. My question is how can i make sure the MAS is the problem before a buy a new part? b/c the a new MAS is $240.00. Thank you.

 

The cheapest way is to replace it with a known good one to see if the code returns. Not easy unless you know someone with a similar Volvo.

 

Hello, i replaced the MAF sensor, but it is still hesitating when accelerating from a standstill. THe MAF code went away, but i still have the code saying "Bank 1 running rich" and a new code: P237 Boost Sensor A circuit Low. So far i have replaced: all 4 spark plugs, cyl 3 coil, and MAF sensor. Please help. Thank you.

 

Have you looked it over for broken vacuum hoses? I've found several broken over the years. You can see one in this photo. It's the large L shaped hose that goes from the throttle body to the intercooler (ignore the red square).

 

hello hudini, i found a big crack in the plastic housing where the vac hose connects to the intercooler. the pic u posted is exactly where the crack is. it looks like i may need to replace the entire intercooler, which is a shame since b/c it seems that housing is just glued or bonded on to the intercooler and offcourse volvo does not sell that piece seperately, u have to buy the whole intercooler? can u or someone else post step by step instructions on how to replace 03 S40 intercooler? thank you

 

Can you JB Weld it? I've fixed some crazy stuff with JB Weld.

 

Ok, ya its worth a try. BTW this is what the crack looks like. Do you think JB Weld will work on this big of a crack.

 

As long as you can find all the pieces, go for it. Definitely cheaper than an intercooler. Even if you don't find all the pieces you can use epoxy putty to build up low areas and then use a file to smooth rough edges when dry.

 

2001 V40. 101k miles.

I have had a CEL problem for a long time. The error code always shows up as a P0101. I have replaced the MAF, and the code returned. I have cleaned the new MAF, cleared the code and it returned. I have been living with this problem for about 4 years. On the recommendation of a forum member, I also replaced one of the MAP sensors. This seemed to fix the problem for a while but then the CEL returned. I just carried my OBDII reader in the car and would erase the codes occasionally or frequently.

Fast forward to this week. CEL back on. Codes now read P0101, P0107, P0301, P0302, P0303 and some others. Car began to stall at lights and could barely run 60 MPH on the highway.

I broke down & took it to a local shop. They traced it to bad MAF & one bad MAP sensor. They replaced both & claimed this fixed the problem. $589 later, I have my car back. I hope this really did fix the underlying problem. I guess many people are used to getting unpleasant surprises from their repair shops. I'm not. I try to do as much work on my car as possible but diagnosing this problem was beyond my ability.

The shop also highly recommended using at least 91 octane gas. They said that this car is one of the most finicky of all Volvos when it comes to gas.

I hope my problem is gone for good.

 

Need to get the L or S shaped hose that connects here. Regular vacuum line too small. Is there a part # for this hose.