I bought a 2002 volvo s40 used from a private seller just about 2 years ago, and I've had the same issue on and off with it since. Every once in a while, the car will have the up arrow next to the check engine light blinking. It typically starts with a "hard shift" (Sorry if my terminology isn't that technical/correct...21 year old female college student here) and then will move very sluggish. When I shift from park to reverse, or from drive to reverse it's a very hard shift. I haven't noticed a specific thing that sets this off, sometimes it's while I'm driving at highway speeds, sometimes it seems like when I shift quickly from reverse to drive, and sometimes there seems to be no reason at all.

Eventually, the arrow will stay blinking when I start the car, but the car drives fine (accelerates like it usually does, no hard shift into reverse). After a few more times of regular driving, the arrow disappears.

I've always just chalked this up as a "quirk" about the car, since it's more annoying than anything, and hasn't caused any damage that had to be fixed right away. I'm getting a little nervous now, though, because it seems to be happening more frequently. It used to happen every couple of weeks or so, but for the past week-2 weeks-ish it seems like as soon as it's back to normal, it starts acting up again.

I've read that it might be a bad PNP or selenoid? I also read that you can clean the PNP switch, but is this something I can do while I'm away at school on my own? I won't be home for another month and don't want anything bad to happen, as I don't have the funds for a costly repair or new car at the moment. I'm just hoping that it's not going to die one day randomly while driving to or from school and leave me stranded.

I hope that you guys can help me! I love my little car and don't want to see her junked if I can prevent it!

 

That light means there is a fault stored in the Trans Control Module. You'd need to have the codes read to know where to start. If the acceleration is weak when the light is on, the trans is in limp home mode to prevent damage.

 

First, you need to get your codes read.

Second, from your description the problem is probably your PNP selector switch. When the PNP is malfunctioning your transmission is forced into third gear. This happened to my '00 V40 and I found it to be undriveable like that.

This problem will not fix itself. It will cost money to fix. You can start to take control of your problem by buying this code reader from Amazon for $19.67 shipped. Just make sure you buy it from one of the sellers on page 2 of the seller list that ships from the USA by Amazon Prime. .

When you get it, read your codes (it's easy) and post them here.

Where are you located, btw?

 

As a quick fix, you can try "rowing" the shifter from Park to 1st (Lo?) to Park quickly about 20 times to see if that can clean up the PNP contacts. That may be enough to get you out of limp mode and buy some time for you to replace the switch.

 

I do have a code reader at home, my father does the majority of the work on my car. Problem is, I'm about 2.5 hours away and won't be going home for about a month. I'm just hoping that my car will last until then. Ive read the codes before, I don't recall what they were off the top of my head but I may have to paper in my car somewhere.

I've tried doing the "rowing" thing and it hasn't seemed to help, but I'll try it again.

I'm in New York, for the person that asked also.

 

Its a long shot but there is a W button next to the shifter, make sure it's not pushed in or gummed up with old coffee sometimes they get stuck. I had similar problem and took it to the shop, in 10 minutes they cleaned that switch and cleared the code and everything was fine - till the next thing. if it stays in the W Mode too long I was told it will throw a code. Good luck I have a love-hate relationship with my *** 40 (sorry I'm using a voice translator and it translated S into what you see which put a smile on my face and seemed a better truth) . Spend way too much time on the hate side with the check engine light on. good luck Suggest you buy a camry...

 

Unless the code reader can communicate with the TCM, it won't be of much use.

 

While you won't get TCM codes, you do get a lot of useful information. When my PNP failed my standard OBD-II code reader showed P0705 and P1618.

P0705 Transmission Range Sensor (PRNDL Input) Circuit Malfunction
P1618 Fault in Lead between AW 50-52 and Motronic 4.3 (MIL Requested)

That was enough to diagnose the PNP failure.