S70 P0133 after SAS Diode Install

98S70T5 · Post by **98S70T5** » 17 Jan 2021, 09:05

Guys, I tried doing all the reading I could on SAS delete info before asking a question.

My car has had the SAS code in it the entire time my grandpa owned it (because it runs fine why would I fix it). I got tired of staring at the light so this weekend I pulled the ECM and soldered in the correct diode (in the correct direction to the correct pins). Removed the ECM again to electrically test the installed diode to make sure I didn't burn it up during soldering. It tested fine.

The light went away and everything seems just fine and no codes for SAS system present. However, almost like clock work (Have reset the light 2 times now) at 60 miles while running/driving/warmed up the CEL will come back on and I found it to have a P0133 code (up stream 02 sensor slow to respond code). My code reader will run an 02 tests and it shows passing on both so maybe that points towards a vacuum or MAF sensor issue? The MAF seems quick to respond on the live data portion of my scanner.

Is there any chance this may be related to the diode install? From my reading I have read codes such as this could be related to a bad 02 sensor/wiring/corrosion at the connectors, dirty MAF sensor, or vacuum leaks. I can't say if this code was in the car before. Any other time in history its been hooked up to a DCT reader it has only shown the normal SAS failure code.

Also FYI, the only disablement of the SAS system so far was unplugging the pump to make sure the Diode worked before I went any further. Will further investigate the connectors etc and I will be doing a PCV service next weekend so I can poke around on all the vacuum connections.

Thanks in advance.

EDIT: Forgot to mention, for the last 30k miles the car has ran fantastically (outside of many, many, other unrelated issues). It averages about 22-23 mpg in the winter and 23-24 in the summer with 28-30 mpg on long highway trips. Hand calculated to verify the MPG meter. It's always withing .5 mpg +/-.

Post by **wizechatmgr** » 17 Jan 2021, 17:45

Check for a VAC leak. When I had the dipstick out on my 98 it would set that code.

Post by **erikv11** » 17 Jan 2021, 21:33

Seems unlikely to be related to the SAS delete. I think you are on the rigbht track - vacuum leak, connector, MAF; something that makes it run lean.

You'll get a chance to stare at this one when you do the PCV: how is the vacuum elbow at the passenger side of the intake manifold? I'd replace any/all suspect vac lines when you do the PCV.

98S70T5 · Post by **98S70T5** » 18 Jan 2021, 07:02

Thanks for the info. The hose looks just fine and I can't hear any extremely apparent vacuum leaks. Although, until I stared messing with the SAS I never realized the vacuum tree has had one open hole presumable for the entire time we have owned the car. I covered it up while I was poking around the other day and it seems to idle a little lower and smoother and cured an ever so slight off idle stumble if you rev it with a lot of pedal.

That hose you speak of is part of the FCP kit when ordered whole correct?

Plan is to thoroughly clean all of the intake tract (MAF sensor, tubes, PTC valve, etc) while I am doing the PCV service. Also, going over any suspect vacuum lines etc. Rear cams seals planned as well.

A day ago I did disconnect the white/purple vacuum line that runs the canister for the SAS exhaust valve just in case that was causing some sort of issue with the exhaust air. No light yet but I haven't driven it 60 miles yet.

Post by **abscate** » 18 Jan 2021, 07:30

That takes a while to codes.

Codes are all software driven, they aren't hard wired analog sensors that detect faults.

A set of conditions {Q} must occur N times over time interval T , then code Pxxxx is set ( or more accurately ECM-xxxx which then may or may not set an OBD CODE

98S70T5 · Post by **98S70T5** » 25 Jan 2021, 06:42

Ok, good news here. I think (hope) I found the smoking gun related to the P0133. This weekend I did the full PCV service with all genuine parts.

Before removing the intake I was taking a look at all the bolt locations with my light and noticed that the vacuum hose on the passenger side intake had in fact rotted off and was open. Keep in mind, the car had also been missing a vacuum cap on the tree for nobody knows how long too (but that was covered at this point).

All the existing vacuum hoses were in pretty good shape except one so they all went back on with fresh clamps etc. The job was actually pretty easy other than getting the front vacuum hard line out of the fuel rail. I didn't want to mess with replacing any of the injector seals since they are just fine as is.

Before the service, the car would ever so slightly inflate the glove on the oil filler at idle but not enough to build pressure inside of it. Now, the glove just lays flat with no pressure whatsoever but it doesn't suck it in like some of the videos I have seen on P2s.

The PTC was surprisingly clean so it took just a little clean up. The block vent and drain were also very clean. The drain was wide open and just needed a wipe with a rag and brake cleaner. The upper had a slight amount of build up on about the bottom 1/4 of the passage. Quick scrape and some brake cleaner/rag and it was good as new.

For good measure, I removed and cleaned all the turbo hard lines, throttle body, as well as the air cleaner to turbo hose.

In hindsight, I probably didn't really need any parts. Could have done the 5/8" mod and ran a dedicated small vacuum line to the PTC but it seems to be working closely to as designed so we will roll with it. I also noticed, the car seems much more responsive in the low to mid range than before. Maybe an outcome of the MAF and 02 sensors communicating properly with the vacuum leak at the intake sealed up. Idle is noticeably smoother with all the leaks sealed up. 70 miles or so without CEL so far but time will tell. Will read any DTCs later today to see if there is anything pending that hasn't set the CEL yet.

Thanks for any info from before.

Post by **abscate** » 25 Jan 2021, 07:08

It’s human nature to assign cause and effect, or in Latin

Cum hoc ergo propter hoc....loosely translates as “ I am now in hoc because of buying too many Volvo parts”

98S70T5 · Post by **98S70T5** » 25 Jan 2021, 07:16

abscate wrote: ↑25 Jan 2021, 07:08 It’s human nature to assign cause and effect, or in Latin

Cum hoc ergo propter hoc....loosely translates as “ I am now in hoc because of buying too many Volvo parts”

Ha, believe me. The PCV parts are just a drop in a very large bucket of money/time.