DIY: Troubleshooting S.A.S. and How to Replace the Famous Fuse # 107!
- I have emission codes P1421 and P1423 (S.A.S. codes saying not enough air is injected into the exhaust during cold start), which is very common for car this age 10y/100K miles.
- In order to understand the S.A.S. system, you need to read the attached pdf on S.A.S.:
---> In brief, when engine is cold, the Air Pump injects additional air into the exhaust to reduce pollutants.
---> The Air Pump is designed for high output but short run, so it injects air for anywhere between 2.5 seconds and 105 seconds or so, depending on engine temp.
- These are PNs for 1998 528i, listed only for reference, later years are slightly different. This is taken from www.realoem.com:
* Electrical Valve; PN 11747537612 (about $45)
* Air Valve: PN 11727540467 (about $110)
* Air Valve Gasket; PN 11727505259 (about $4)
* Pierburg Air Pump; PN 11721427911 (about $250)
* Air Pump Relay (K6304): schema is 85-86 and 30-87a-87, PN 12631742690 (about $8)
* Fuse #107: 50A Special Fuse: BMW PN 61138365901 ($4.00); Napa PN 782-1144 ($4.00). The BMW Fuse is covered in black and you cannot check it with your naked eyes (need Voltmeter or Ohmmeter to check). The Napa Fuse is see-through: within a glance you can see the fuse is good or not. I prefer the Napa Fuse. See pic:
- To be sure the Air Pump is bad, remove it and apply 12V to the 2 pins, if it does not run, either the bearing is seized or the motor is gone. You have 2 options:
1. New Pierburg Air Pump is about $250.
2. Rebuild the Air Pump using a standard bearing SKF 626 (ID = 6mm; OD = 19mm ; W = 6mm). Complete Air Pump Rebuild Info is here:
This is the sequence of S.A.S. system when you start the car cold:
- ECU sends signal to the Electrical Valve (this Valve sits under the Intake Manifold), which in turn opens a small channel to allow vacuum from the Intake Manifold to be applied to the Air Valve (which sits on the Exhaust Manifold)
- At the same time, signal is sent to the Relay to close the 85-86 "primary" circuit, which in turn closes the 30-87 "secondary circuit". In general, the "secondary circuit" in most Bosch relay circuits controls the high current flow.
- In the case of the S.A.S. Air Pump, the 30-87 circuit is controlled by the Fuse # 107, which itself is under the passenger's seat, thanks to the BMW engineers who designed this car with beer and bratwurst!!! In any other car, replacing this fuse is not hard because it is usually located under the hood. In the E39, Fuse 107 is a bit tricky to get too, but not too bad.
SOME DIAGNOSTIC PROCEDURES:
- Check the small Vacuum line leading to Air Valve, it is usually cracked with time/heat.
- To check Electrical Valve, during cold start, Disconnect (D/C) the small vacuum hose and feel for vacuum, there should be some vacuum from the small hose b/c the Electrical Valve opens the port to allow vacuum from the Intake to the small hose. Now re-connect the small hose.
- Air Valve and Gasket testing: Disconnect (D/C) the large hose to Air Valve, start engine during cold, after a few seconds there should be vacuum at the Air Valve (feel with your palm of your hand), if not either the Air Valve itself or the Electrical Valve is bad.
- Air Pump Testing: At the same time as above, the Air Pump is activated, so you should feel air blowing out of the large hose that you just disconnected above, if not, then the culprits are:
a. The Fuse #107 is blown. When this happens, usually something else is bad (like Bad Air Valve allowing water from exhaust to enter the Air Pump, destroying the bearing is blown ---> the Air Pump is dead. If the Air Pump is shorted electrically, the new fuse will be blown again. So if the fuse is blown, investigate it further. In my case the Air Pump was seized.
b. S.A.S. relay is bad (rare).
- Before getting to Fuse #107 under the passenger seat, check the S.A.S. Relay and its connector first!!! The Main Fuse Box is under the passenger side Cabin Filter. Remove the Passenger Cabin Filter Housing.
- Using Allen keys, open the Plastic Cover and you will see the setup below with all the main relays and some fuses here. To check the S.A.S. Relay, remove it & check for continuity between 30 and 87a, it should be 0 Ohm. Now apply 12V to 85 and 86, 30 and 87 (not 87a) is now connected.
- Now check the Relay Connector, take note of the relay pinout, then copy it to a piece of paper because when reading relay upside down, it is very very easy to get all the connector terminals mixed up! By copying the terminals numbers (basically mirror image of the relay) to a piece of paper, you eliminate error! Over the years, I have learned this the hard way, so trust me with this copying to a piece of paper. There should be 12V to #30 terminal all the time. See pic:
PROCEDURE TO REPLACE FUSE #107 UNDER PASSENGER SEAT:
Now that you have determined that there is no power to terminal #30 in the Relay Connector itself, time to check and replace the 50A Special Fuse.
1. The Trim piece: using flat screw driver pry it up, it is held by 3 White clips.
2. The Seat is held by four (4) Torx #50 bolts, remove them but no need to take the seat out of the car.
3. The Vertical Trim piece: undo the bottom part only to allow the carpet to be folded back.
4. Note how the carpet fits (the front carpet piece slides under the rear piece).
5. Fold the carpet back and place a brick on it to hold it there to free your hand. You will see a Styrofoam insulation piece. In order to remove the Styrofoam in its entirety, you have to remove the plastic tunnel (HVAC Tunnel), which is more work! I bypassed this step: I leave the plastic tunnel alone but break the styrofoam at where it meets the plastic tunnel b/c it is a only a piece of insulation, nothing fancy about it.
- Use a short piece of wood to prop the seat up about 12".
6. Now you see the Electrical Distribution Center, remove the white plastic covers to expose the Red (+) connections. Ground (Brown Cables) is just to the Left of this distribution box.
7. Fuse Block has a total of 8 fuses. Fuse #107 is on the far Left. See picture:
8. To test the Fuse, use a Voltmeter (not Ohmmeter for now).
9. Note the Large Red Feed Cable side, it feeds power to the electrical block where it branches out. So probing on that side must read 12V or so. Now probe the other side of the fuse, it should read 12V as well, if it reads 0 volts, the fuse is bad.
10. To replace the 50A Fuse, it is held by 8-mm nuts and square washer. Use a small hook to hook it out. Remove the fuse and confirm that it is bad with an Ohmmeter: when a fuse is bad it reads infinity Ohms (open circuit).
* CAUTION: this circuit is always "hot" with 12V, even with key out of ignition! If you are not comfortable working with "hot" wire, then disconnect the red cable from the trunk battery. I did this whole thing with the battery connected, just pay attention not to touch any ground while removing the 8-mm and 10-mm nuts.
11. The medium-sized red cable feeding separate electrical items in the car is held by a single 10-mm nut.
12. NOTE the torque for these nuts, basically tight and snug a bit:
* 8-mm nut: 8 Nm
* 10-mm nut: 15 Nm
13. Now you need to address the Air Pump. Either buy a new Air Pump or rebuild it, otherwise this fuse will blow again! Info for Air Pump is mentioned above.
That is all boys and girls, not too difficult if you know what you are doing!
Last edited by cnn; 06-05-2010 at 11:12 PM.
CNN, I haven't seen this error yet, but man, when I do, I can reference this in the future. Thanks for taking the time to write this up!
Mods, Please post to E39 DIY section...
Last edited by BlackBMWs; 05-30-2010 at 10:43 PM.
1999 540it - Schwartz II/Sand Beige, style 5 rims, Conti DWS 235/45 tires, Billy HD/Sports, Stoptech S/S BL, F1 Pinacle 35% tint, Zionsville Cooling kit
1998 318ti Cali Sport - Schwartz II/Schwartz Anthratz, staggered style 23
1997 318ti Sport - Schwartz II/Schwartz Anthratz, staggered style 68 ,
1995 318ti Active - Alpineweib III/Schwartz, squared style 32
1994 325i - Bostongrau/Tan, Billy Sports, H&R springs
1991 318ic - Schwarz/Anthratz Stoff, Bilstien HD, Z4 3.0 SS, Magnaflow, S/S Stress bar, x-brace, M20 FW, Elipsoid/HID, K&N
1995 318ti Sport Schwartz II/Schwartz Anthratz - Sold
1985 635CSI - Schwartz\Sand - Sold
1984 533i "Max" - Schwarz/Schwarz, - Sold
1984 318i - Champagne/Tan, Stock - Sold
Well, I have owned a few Volvo's BMW's and by the time you reach 10-12y or 100-120K, soon or later you will get these S.A.S. problems!
Great post!! The detailed pics really help. I don't have this problem (yet...) but, I do have some problems with my wipers and now I know where the relay is if it needs to be replaced. I have checked several other fuses, motors and relay so I think you might have helped me solve my problem!! Thanks again!!
I had the very loud screaming sound, went to do the diagnostic and realized the large hose from the pump to the valve had been disconnected, but only slightly as it looked connected and was resting in the correct location. I think when I was changing my timing chain tensioner the other day, I must have bumped the release for the hose on one side. After I fully clicked the hose back in place (a surprisingly amount of force was required) , it went back to normal. While only a couple of cold starts since then, it seems to have been the issue. So when in doubt do the diagnostic that cnn has in the awesome writeup, but perhaps before releasing the clip on the large hose, check to see if its tight while the engine is off. Mine was very obvious. On the 540 I had to remove the airbox to get a clean visual and get enough leverage with my hand to get the click.
Nice job cnn... Thank You
Just to let all the wagon dudes out there know. The 107 fuse is behind the sub woofer in the trunk so we don't need to pull the seat up. I went through this whole thing last weekend to find I had a short in the power wire somewhere between the relay and the 107 fuse in the back. Weird. Has anyone else had a good fuse and still no power to the relay?
I check to see if im getting power to the relay and i get power to pin 65 but no power to pin 30 is there more then one fuse for the air pump
I forgot to update this thread, in Bimmerfest, read the thread by cn90 and billj3cub. Threads #52 and #54.
#87 is HOT all the time, and #30 go to Air Pump (so no voltage at #30); this is in contrast to the "Published Diagram"!
I just replaced the air pump relay i hear something clicking
So my question was can u hear the relay for the air pump
Until I figure out how to do a SAS Delete (an entirely different topic), I need to fix this SAS codes of P1421 and P1423. This may be the last time I spend money on this goofy SAS system. Enough ranting back to work.
DIY: How to replace the Electrical Valve: PN 11747537612 (about $45 online for Pierburg brand).
Pic 1a: Parts: Air Valve as mentioned and OBD-II Code Reader ($25 on Amazon.com).
Pic 1b: With car cold on startup, Air Pump should run.
Best is to disconnect the large hose at the Exhaust Air Valve, a lot of air should come out during cold start (Yellow Arrow), if not either Pump is dead or Fuse #107 is blown (see the beginning of this thread)
- In my case a lot of air comes out so I know the Air Pump is good.- But when checking the vacuum hose next to the Exhaust Air Valve, there is no vacuum, so I know the Electrical Valve is bad.- Time to replace the Electrical Valve.
Pic 1c and 1d: Remove the cosmetic cover (pry the round cover and remove the two 10-mm bolts).
Disconnect the PCV Hose by squeezing on the "wider" part of the Retaining Ring why rotating the hose to work it loose.
1. Disconnect the electrical connector.
2. Using a flat screw driver to gently pry between the valve and the metal bracket: life the old valve upward to remove it.
* the "downward nipple" feeds the hose to the Exhaust Air Valve.
* the "side nipple" feeds to vacuum hose that goes to Intake Manifold.
This is perfect time to change new vacuum hose.
* Then erase codes.
* Do not forget to re-connect all hoses (vacuum, large hose to the Exhaust Air Valve, PCV hose etc.) before starting the car.
That is all boys and girls:
Last edited by cnn; 12-22-2011 at 10:10 PM.
Hi guys first post so I'm expecting great things.
My 02 325xi just flipped 150K so I decided to do a fairly extensive refresh..... all fluids, valve cover gasket, cleaned injectors, changed all the vacuum lines. Pulled the intake manifold etc. Buttoned it all up and it ran great but got an SES a couple days later. Peake codes 44 F5 and F6 ... EVAP purge control valve and secondary air flow too low. Cleared codes and light comes back on every other drive cycle now but only with the EVAP code.
I bench tested the EVAP valve and it opens with 12V. Ohms correctly at 26. 12V at the connector. Also now the SA pump is not coming on at startup nor am I getting vacuum from the check valve vacuum line.
Tested everything. The pump activates with 12V input. All fuses are good in the Ebox fuse carrier and the 50A for the pump. Relay bench tests normal with audible click and 30-87 continuity when activated. The only thing I find wrong is I'm not getting 4.4V at pin 85 with key on. I do get 12V at pin 86.
So WTF is my DME toast? I did all the refresh work with the battery DCed. I don't have any DME codes. No other codes for that matter. Car runs great.
Is there some connection between the EVAP code and the SAS not running? Any ideas?
just to save on my to do list
2003 525i Sports Pkg M54 Auto E39