Hi all, I adopted another S70 last week, a 1999 S70 T5 with 70K on the odometer, and looking very clean inside, under, and out. The check engine light was on when I first looked at the car, so I "test drove" it to my house and hooked up my OBD2 system, and the codes read "P1171" and "P1174," "System too lean." I figured it was just a bad MAF, since my other S70s have had the same codes with MAFs going out.

I ended up getting it for a really good deal, using the check engine light being on as a negotiating point, figuring I knew exactly what was wrong with it. Well, I went to the dealership that is closest to us to pick up a new MAF, and I went ahead and asked them to do the T-belt and accessory belts since they had not been done yet, and I wanted it done as PM. I also asked them to confirm the MAF diagnosis I had made...

After they finished the T-belt (can you believe they did it in less than an hour!?!? Took me 3 hours on the one I did myself on a '98), they hooked up the computer, and they got different codes of course, but theirs were more along the lines od indicating that a nipple under the manifold was clogged. I let them go ahead and clean it, which apparently required removal of the manifold. They reset the check engine light, and it appeared fixed.

Well, on the way home the check engine light came back on, again reporting as "system too lean." I ordered a new MAF, put it in, and the light has been off since. My reported average MAF readings on the OBD2 are also much higher than previously (now at average 1.2 under city driving, and 0.75 at idle, with max of 2.4 and min of 0.2; earlier values were never getting above 1.5 or so).

Anyways, it appears to me that the S70s just need new MAFs ever 60K or so. Has been true for 2 of the 3 S70s I have had (one of which is not yet at 60K, at least it was not when I sold it 6 months ago, but I bet it will be 3 out of 3 here in the next year or so). Fortunately they don't cost much, only $157 wholesale, $210 retail, at least at the dealerships I have used.

Don't know if this helps anyone! I love the S70s, thats why I keep adopting them, but they do have their quirks:)

Thanks,
Vos

Hello Vos,
Thanks for the post..had an MAF fail on my 99 S70 at 48K with variable idle. Out of interest, was your idle affected? Now my check engine light is back on at 62K and my idle again is not steady when the car is at temperature (varies from 900 to nearly stall continuously). Any thoughts?
Much appreciated
rpscdn

rpscdn,

Yes, my idle was indeed a little rough, and even at cruising speed on the highway it was a little rough (just a little though). The idle did smooth out a little when the dealer cleaned the throttle body and the manifold nipple (I still don't know exactly which nipple they were referring to), and I think that was indeed 1/2 of the problem, but it also needed the new MAF. Now it is running great!

FYI, the dealer tech I talked to (who was extremely bright and really knew alot about the car's electronic systems) said he typically just replaces the throttle bodies on the 99's, though he did admit that you can usually clean them at least once with success (he cleaned mine, but warned it may need replacing in another 30K or so). The tech did show me their VADIS output info for the car, mostly focusing on the MAF values. Apparently low MAF values can be decently out of range before triggering a MAF specific OBD2 code. I guess the MAF operates on a wide range, and the average has to drop fairly far to get a specific MAF fault. The O2 sensors though definitely seem to pick up on the lean condition's P1171 codes before triggering the MAF fault. On one of our '98 S70s I saw both a MAF code (I forget the number) and an O2 code. That was the easy one to diagnose:)

I have only had my 99 for 2 weeks so far, so I have not had much time to learn its systems and its differences from my 98's. So far it appears to be mostly the electronics and the fly-by-wire technology. Cool stuff, I just hope the reliability is good in the long run. Look to see me posting lots of more questions, and maybe a few answers:)

Thanks!
Vos

Hello Vos,
Many thanks for the great info.....looking forward to the continued posts. Will let you know how and if my situation resolves itself.
rpscdn

Hi Guys,

I had a CEL for about 4 months and was pulling my hair out till BLUP
told me to get an Equus codes reader and see if I get and P1171 and sure enough I did. He this happened to him and it was his MAF. He replaced his and all is well and I replaced mine and all is well. [ $162 at Brentwood ]

Moral of the story. P1171 = new MAF and I'm sure more and more will be popping up as times goes on. I also have a hunting idle. Rich over at Bay13 feels it is probably the Electronic Throttle Module that needs a clean. We don't have the traditional throttle bodies that our cousins have on the 98's and older. Our Fly by wire technology is a whole different ballgame and I think the bugs will rise up pretty soon.

Still to chicken to do it as you may have to remove to radiator fan to get at the little ETM and it's intake using some carb cleaner on a rag. Will wait till more BBer's do the cleaning and get the procedure down. Can be tricky.

rd

--
99 c70 hptm 37k miles