98 S70 T5 So why did the check engine light not go off?

SpeedyPete · Post by **SpeedyPete** » 06 Apr 2014, 17:43

Hello all out in Volvo Land

The check engine light came on in my daughters car and I pulled a P0108 code. I replaced the MAF with a new Bosch unit and cleared the code. I restarted the car and the check engine light came on again....Hmmm..... I tried to reread the codes but none came up! So why would a check engine light come on with no codes in the system? I have erased all codes a second time and still the same result. Check engine light on and no codes in my reader. Your thoughts will be greatly appreciated.

Post by **jimmy57** » 06 Apr 2014, 18:22

Most scanners will not display the code for the transmission requesting the CEL be turned on. You could have a Trans code.

SpeedyPete · Post by **SpeedyPete** » 07 Apr 2014, 09:06

Thank you Jimmy I'll check the trany. Is their a transmission low level fluid sensor on these cars? Unfortunately this is a long distance diagnostic with my daughter. She is in San Diego and I am in Santa Cruz CA.

Post by **rspi** » 07 Apr 2014, 09:40

Ouch! Hate when that happens (distance).

Tell her to keep driving it. The code will surface, likely pending.

Post by **mecheng** » 07 Apr 2014, 10:03

Sometimes my code reader will not clear the code, I have to disconnect the battery for a couple of minutes.

Post by **cn90** » 07 Apr 2014, 10:04

Maybe I am missing something but P0108 is for MAP not MAF problem!
So don't throw away your old MAF yet...

You may want to review this thread below:

Error Code p0108:
https://www.matthewsvolvosite.com/forums ... =1&t=28164

PS: PN 1275342 is the MAP sensor, if you don't want to remove it and solder the joints (as in the link), then ebay has some for $15 incl. shipping.

Post by **erikv11** » 07 Apr 2014, 10:32

rspi wrote: ... Tell her to keep driving it. The code will surface, likely pending.

Negative, codes do not "surface."

Pending codes are just that, pending not set, and they do not trigger the CEL. jimmy57 knows his stuff: if the check engine light is on, and no code shows on your reader, then the code reader is not capable of reading the code. Don't be fooled by a code that does later surface, that would just mean another code has been thrown, without telling you what is causing this CEL. Disconnecting the battery may well erase the code though, you could try that and see if/when the CEL comes on again.

There are (many) scanners than can read transmission codes, your best bet is to get that done. That may require a trip to a shop this time, at least for the code.

There is no trans fluid level sensor.

Post by **rspi** » 07 Apr 2014, 13:15

Well, this ACTUALLY HAPPENED to me a few days ago. Reset the CEL, the CEL did NOT go away but there was NO CODE in reader. Five miles later THE CODE surfaced. Once the code APPEARED, we dealt with the problem, now the CEL and the problem are both gone. Not all scanners manage PENDING CODES well.

J

Post by **erikv11** » 07 Apr 2014, 14:00

More like ignoring a transmission code for 50 miles could be troublesome.

SpeedyPete · Post by **SpeedyPete** » 07 Apr 2014, 14:23

Hi Guys! Is CN90 correct in his assumption that the P0108 code is for the MAP only or is it also for the MAF Sensor? This is interesting because the code cleared after the new MAF was installed. Hopefully this afternoon my daughter and I will have another phone diagnostic session. Thank you all. Have a nice day!