1998 V70 P0413 SAS Valve A open diagnosing

dynamaniac · Post by **dynamaniac** » 27 Jun 2020, 13:37

Time for this Volvo n00b to learn yet again... I just got my first CEL on my 1998 V70 NA, 156k miles, and pulled up trouble code P0413 with a generic bluetooth OBDII reader.

The CEL came on after taking my first drive of over 20 miles in months. I took the short drive to a trailhead, went on a hike, and when I started the car to return home, the CEL was on. Engine sounded normal and had plenty of oil, so I drove home.

A few days later, after identifying the trouble code, I removed the battery to take a better look at the air pump. I couldn't find much documentation about troubleshooting the air pump (lots of people seem to bypass/delete SAS instead), but I didn't see any loose wires. After re-connecting the battery, the CEL was reset.

Maybe a half-dozen short drives later, the CEL was still off. I figured maybe there had been some random blip in the circuit and the running engine still sounded normal.

I took a long drive, 250 miles, for a 4 day backpacking trip. When I started the car for the return drive, the CEL was still off. But after taking a 30 minute rest stop, in the intense 105degF heat of Redding, CA, the CEL came back on. I checked the oil at a gas station, no issues, engine purring smoothly, so I drove home. Same trouble code, P0413.

One last thing, I've noticed that the car occasionally fails to "chime" when the key is turned to position A. Ever since I had some misfiring/starting issues a few years ago, I've tried to always let the chime end, priming the gas lines, so this seems a bit unusual too, but not outside of what I've experienced with the car. Starting is a bit slow when the chime fails to initiate, which I presume indirectly means no gas is being primed.

1) I still need to check that the air pump is, in fact, working. Should I do this with the hood open and have my wife start the car while I listen for something in the vicinity below the battery?
2) Is there a good diagram of how the air pump and its various hoses/valves/wires should look in the engine bay?
3) Why might the CEL / this trouble code trigger intermittently? Does the ECU monitor the SAS intermittently? I know it's supposed to run only at start, but the circuit might need to be closed all the time to not trigger the CEL?
4) Am I completely missing some aspect of how to approach this issue?

I live in California so SAS delete doesn't seem to be an option. My next smog check is in October, so I have a few months to resolve this.

Any and all advice from this forum is always greatly appreciated!

Post by **misha** » 27 Jun 2020, 16:46

Air pump works for a few seconds after starting a cold engine and sometimes at prolonged idle when ecu ask for it.

You can delete SAS and still pass inspection with soldering a diode in ecu and leave everything as it is.
If your problem is SAS valve,you can also block it and leave all components in the car.

This way,ecu will not pop a code for it and check engine light will not be ON because,when you do a "diode" SAS delete,ecu will think that is is working properly when it ask for it.

Fuel system is designed to be primed before starting the engine....turn the key to posII,wait 2 seconds while fuel pump prime the system and then start the car.

Not doing this will result in longer cranking and eventualy,failure of fuel pump relay which is full of electronics.

Post by **erikv11** » 27 Jun 2020, 17:16

dynamaniac wrote: ↑27 Jun 2020, 13:37 1) I still need to check that the air pump is, in fact, working. Should I do this with the hood open and have my wife start the car while I listen for something in the vicinity below the battery?
2) Is there a good diagram of how the air pump and its various hoses/valves/wires should look in the engine bay?
3) Why might the CEL / this trouble code trigger intermittently? Does the ECU monitor the SAS intermittently? I know it's supposed to run only at start, but the circuit might need to be closed all the time to not trigger the CEL?
4) Am I completely missing some aspect of how to approach this issue?

I live in California so SAS delete doesn't seem to be an option. My next smog check is in October, so I have a few months to resolve this.

Any and all advice from this forum is always greatly appreciated!

Mostly I agree with everything misha said. I'm a diode devotee. People in CA have definitely used the diode.

1) I actually seem to recall that at startup, the pump only runs when the car is moving. Catch-22 there. It's not often people keep the SAS I don't remember those details; search here there are many threads about it

. I would check the pump by unplugging it from the relay and applying 12v from the battery directly to the hot lead. If it works it will whir right up.

2) Yes, for a diagram there is a white sticker under the hood of your car that tells exactly how yours was/is equipped. The smog tech looks to this sticker when they check to see if the factory equipment is present.

3) Most often, because the SAS valve is dead, and the pump is full of water (or filling), and cooked. I'd check that.

4) I think you are on track. Bottom line is first test if the pump is good, then if the vacuum lines are all intact. 20 year old rubber doesn't always hold up well. Usually the problem is the SAS valve has gone out and killed/killing the pump.

Post by **jreed** » 28 Jun 2020, 07:41

I'm impressed that the SAS trouble code was the first one you've had on a 22 year old car -- super reliability!!
Could the lack of a chime at start up be due to a worn out electrical portion of the ignitiion switch?

Post by **xHeart** » 28 Jun 2020, 08:18

This thread may help a little viewtopic.php?f=1&t=89332

dynamaniac · Post by **dynamaniac** » 28 Jun 2020, 14:15

I should've clarified, first CEL I've needed to deal with since getting the car used 4 years ago

but no doubt, I've been very impressed with its durability over these years. Four years still seems like a long time with no other CEL for a 22yo car!

The chime USUALLY occurs, but sometimes it doesn't and I'm left scratching my head.

Thanks for that thread, xHeart - I seem to have missed it in a few searches of the forums the other week. The images and tips are particularly useful.

Perhaps a novice question but, assuming that no other trouble codes are coming up, and the car seems to be operating fine, I can continue to drive around despite the SAS issue/CEL until I have time to really troubleshoot, right? (No risk to the car)

Post by **xHeart** » 28 Jun 2020, 14:53

dynamaniac wrote: ↑28 Jun 2020, 14:15 I should've clarified, first CEL I've needed to deal with since getting the car used 4 years ago :D but no doubt, I've been very impressed with its durability over these years. Four years still seems like a long time with no other CEL for a 22yo car!

The chime USUALLY occurs, but sometimes it doesn't and I'm left scratching my head.

Thanks for that thread, xHeart - I seem to have missed it in a few searches of the forums the other week. The images and tips are particularly useful.

Perhaps a novice question but, assuming that no other trouble codes are coming up, and the car seems to be operating fine, I can continue to drive around despite the SAS issue/CEL until I have time to really troubleshoot, right? (No risk to the car)

Keep an eye on it. It won't stall because of SAS malfunction, unless someone says otherwise.

Post by **erikv11** » 28 Jun 2020, 15:03

I agree, should be no risk to the vehicle.

Post by **misha** » 28 Jun 2020, 15:08

Actually...if SAS valve is stuck open it will let water from condensation to air filter and through the MAF...killing the MAF sensor.

Also...that condensation gets into cylinders,producing intermittent misfire.

I had this long time ago.

Post by **scot850** » 28 Jun 2020, 15:12

All the SAS does as far as I recall is to pump more air into the exhaust to 'clean' the exhaust gasses and reduce bad emissions during the warm up process when the engine runs richer. All that happens when it does not run is your exhaust gases get dirtier until the engine gets warm. Obviously fitting the diode just bypasses the need for this to prevent the CEL being set, but otherwise should not affect the cars running.

The failure of the pump at this point is only amazing it has lasted this long. Buying a used one from a junkyard is as likely to have the same problem unless you can find something hinting at it being a newer replacement. Also, if you replace the pump it is pointless unless you replace the valve as well.

Always happy to be corrected!

Neil.