Two Sensors Die at Once? 98 v70 T5

Post by **WagonLagan** » 20 Jun 2017, 20:26

Hey all,

I would really appreciate some guidance.

So my Check Engine light came on unexpectedly the other day. The code was P0108.

Then the next day, the car started sputtering and trying to stall out really badly. Keeps going into limp-home mode. Sputters really bad at low RPMs.

Checked the code again, and now there is P0108 and P0122.

Got the codes run at AutoZone and they came back as:
P0108 Manifold Absolute Pressure/BARO Sensor High Input
P0122 Throttle/Pedal Position Sensor A Circuit Low Input
And it also mentions this:
Code P0108 indicates that the Manifold Absolute Pressure/BARO Sensor had high voltage input for a predetermined period of time.

The odds of both of those sensors going out at the same time seems unlikely, so I'm thinking there is a root cause I'm not able to discern.

If you have a thought on what is going on, I'd really appreciate it. This is my only vehicle, so I need to get it back up and running as soon as possible.

Thanks for any help!

Post by **erikv11** » 21 Jun 2017, 03:57

I have had the baro sensor code about three times, but never replaced the sensor. Just reset the code and it went away foe a year or two.

The sputtering matches a bad TPS. If it was me I would grab one from a junkyard (OK I have some spares, same thing) and swap it in. You can also test the TPS with a multimeter, do some searching, but it is a little tricky.

Did they reset the codes at AutoZone? Which one(s) come back?

Post by **WagonLagan** » 21 Jun 2017, 04:55

They won't reset codes at Auto Zone, and I don't have my own OBD II reader to do it.

Thanks so much for that perspective and fast response erik. That gives me a starting point. I'll get myself a new TPS and see if that fixes it up.

Post by **abscate** » 21 Jun 2017, 05:53

Once you start poor running the codes will pop,up like pop corn. Take a look at the wiring on the sensor and a wiring diagram to see if the have a common 12 volts before throwing parts.

Post by **erikv11** » 21 Jun 2017, 10:15

I agree about not throwing parts at it - that's why I said junkyard part. Spare parts are great for troubleshooting, but can be a very frustrating way to go if you are buying them new. So a junkyard baro sensor would be great here too, for troubleshooting. abscate may even have a spare one?

Post by **June** » 21 Jun 2017, 12:38

WagonLagan wrote: ↑21 Jun 2017, 04:55 They won't reset codes at Auto Zone, and I don't have my own OBD II reader to do it.

Thanks so much for that perspective and fast response erik. That gives me a starting point. I'll get myself a new TPS and see if that fixes it up.

I had a 1998 V70 and my husband used to work on it and to rest the computer he would remove both battery cables and touch them together than rehook the battery back up and the engine light would go out until the next problem. Back 15 plus years ago affordable portable code readers weren't around so that was the easiest way to reset the computer after he repaired the problem. June

Post by **abscate** » 21 Jun 2017, 13:14

They won't reset codes at Auto Zone,

Is this a state-by-state thing or by store perhaps?

Post by **FLXC90** » 21 Jun 2017, 13:21

abscate wrote: ↑21 Jun 2017, 13:14
They won't reset codes at Auto Zone,
Is this a state-by-state thing or by store perhaps?

Same here in FL, it's a liability for the store ( aiding and abetting wanton polluters) and we don't have state emissions testing!

Post by **FLXC90** » 21 Jun 2017, 13:22

FLXC90 wrote: ↑21 Jun 2017, 13:21
abscate wrote: ↑21 Jun 2017, 13:14
They won't reset codes at Auto Zone,
Is this a state-by-state thing or by store perhaps?
Same here in FL, it's a liability for the store ( aiding and abetting wanton polluters) and we don't have state emissions testing!

edit-thread-jacking alert!!

Post by **WagonLagan** » 07 Jul 2017, 20:57

Well this just got weirder.

So I grabbed a TPS (Throttle Position Sensor) since that was one of the codes and they cost $20. Threw that in, and it seemed to fix it! Drove for awhile without any issues.

Then it started to shudder/drop RPMs a little again, but it only seems to happen when coming to a stop sometimes, or at least that's only when I can notice it. It hasn't dropped all the way back into Limp mode though, and the shuddering was occasional, but it seemed to slowly increasing frequency.

Yesterday... I took a 40 minute drive, the car sat for 3 hours, then a 40 minute drive back. I'm nearly home, and it starts shuddering a lot more than it has since the TPS replace. It was warm out, about 90s.

Then, my brake assist goes out! ?????????????????

I look in my mirror, and there's some white smoke coming out of the exhaust. I know some white smoke can be normal, but I also know enough of it means headgasket problems with leaking coolant.

So I let it sit for half a day. Coolant levels dropped only by a couple milimeters, and it looks like it was probably leaking very slightly through the coolant bottle cap. I start it up, no smoke. Drive it 10 minutes, no smoke. Another 10 minutes home after the grocery store, no smoke. I started the car with the coolant cap off, no funnel effect (I've heard that's a good way to check for a broken head gasket). Also, the brakes were back.

Can anyone take a guess at what the hell is going on?

It's starting to seem to me like some sort of cascade failure with an electrical root cause. Could fluctuating currents from a dying alternator cause these kind of issues? Maybe it killed a couple of sensors? I have no clue at this point. One of my biggest concerns right now is if it's safe to drive, or am I damaging it while driving?

Thanks much to anyone who can lend some ideas or advice on where to start.