16487 Mass Air Flow Sensor (G70) Signal too High

**gointoscott** · 12-16-2008 08:30 PM

Well I'm getting this code:
16487 - Mass Air Flow Sensor (G70): Signal too High
P0103 - 35-10 - - - Intermittent

What I'm noticing is when I'm going into wot in 5th or 6th gear i will go to full boost (17-18 psi) and hold fine. car pulls strong and smooth. But then the ESP and ABS light will come on and stay on until I let up on the gas. Then after a second or two the lights will go off

I dont notice anything else wrong it runs and pulls fine.

So I did some searching and found from previous posts state that the max the MAF can read is 229 g/sec (well that was for an A4 forum not sure if it is different for our A4's) So when maf reads higher then that it will trip esp light.

I also read that small boost leaks can cause maf to read too high causing this code.

I'm going to check for leaks again, and replace some more of the stock clamps to make sure everything is buttoned up good.

Anyone else have more idea's?

thanks

**AudiSportB5S4** · 12-17-2008 06:21 AM

do you have a Bosch or Hitachi MAF? did you make the hitachi split yet? garage says a 2001, but not all of them had it. Go check, because a faulty MAF can trigger that code, or it can trigger signal too low, etc.

**gointoscott** · 12-17-2008 07:10 AM

I have a 01.5 S4 it has the M box ecu. I am pretty sure i have the better maf, but will check for sure.

I have never had the maf code before. But at same time I dont think the maf has ever been replaced. it has 93k on car right now

**AudiSportB5S4** · 12-17-2008 07:18 AM

Originally Posted by gointoscott

I have a 01.5 S4 it has the M box ecu. I am pretty sure i have the better maf, but will check for sure.

I have never had the maf code before. But at same time I dont think the maf has ever been replaced. it has 93k on car right now

Gotcha, alright well make sure it is the Hitachi, then go from there. I'm not sure with the tune you run if you will be able to do this but with GIAC it is easy to diagnose MAF problems by unplugging the MAF and seeing if the problem persists... So, I'm not sure how your tune will react but you can give it a shot, it won't hurt. Unplug the MAF and see if the ABS/airbag lights come on with in unplugged. If they go away then you know its a MAF issue.

**mholme** · 12-17-2008 07:23 AM

I had that code once when I had a massive leak in my throttle body boot. Yours might not be there, but a boost leak can cause this code.

**Rajan147** · 12-17-2008 04:51 PM

Originally Posted by mholme

I had that code once when I had a massive leak in my throttle body boot. Yours might not be there, but a boost leak can cause this code.

i had the same issue, mine looked like it was on the TB but you could hear the hiss from the bottom, which is kinda hidden. Check for boost leaks asap

**gointoscott** · 12-21-2008 01:24 PM

Well I wanted to update this post incase someone else has this code and does a search looking for answers.

There were coments how this code can come up from a boost leak. Well I did test the car and found a leak here:

It is the brake booster hose

It does go to full boost so the leak is minimal but still it is a leak so I'm going to replace the hose. Dont need to make the turbo's work harder then they have to.

I have noticed that when idling the car has around -18 hgs which really should be -20 hgs so thought there might be a minor leak.

I'll send an update when i replace the hose.

**groovetek** · 01-10-2009 03:13 PM

figured i'd chime in.

what you should do is log your injection time - for me, what happens is, if my injectors are reaching 100% duty cycle, ie. getting maxxed out, and the MAF value keeps increasing, then i get the 16487 code.

this generally happens in higher gears because the load is higher and thus the MAF reading is higher.

good thing my tune was very rich to begin with, so with my piggyback i've scaled all the maf values down quite alot, such that my injection duty cycle no longer maxes out.

you can log the injection time in ms, can't remember which measuring block, but it's quite easy to find. if you find that injection times flattens out at a certain value (ie. for me, 16.32ms) and doesn't go any higher than that even though your MAF values are increasing, then you probably have the same issue as me.

i dont' have the same car, but i think it could be the same issue.

mine is a 2.8 with the PES G2 charger kit.

**gointoscott** · 01-10-2009 05:26 PM

Grovetek thanks for your post. I just recieved a few parts today - n80 valve and brake booster. I'm going to put them in tonight or tomorrow and that should help the minor boost leak I had from my old brake booster. I heard getting rid of leaks can prevent this code.

I will also check the log for injectors with vag as you suggest to see if they level off. I just had my tune adjusted to boost higher (went from 12 to 17 psi) it started throwing this code only after that and only in higher gears as you say.

If i do need to adjust my maf settings, is that something i can do with vag or will i need my tuner to change the settings? hope i can do it.

Thanks again for your post.

**gointoscott** · 01-11-2009 08:07 PM

Originally Posted by groovetek

this generally happens in higher gears because the load is higher and thus the MAF reading is higher.

good thing my tune was very rich to begin with, so with my piggyback i've scaled all the maf values down quite alot, such that my injection duty cycle no longer maxes out.

you can log the injection time in ms, can't remember which measuring block, but it's quite easy to find. if you find that injection times flattens out at a certain value (ie. for me, 16.32ms) and doesn't go any higher than that even though your MAF values are increasing, then you probably have the same issue as me.

i dont' have the same car, but i think it could be the same issue.

mine is a 2.8 with the PES G2 charger kit.

Does anyone know if you can adjust the maf values down using vag-com? If so please let me know how I can do this. I have the full version (3.11)

Hope someone can chime in. MHolme do you know at all?

Thanks

**tuccatucca** · 05-06-2010 08:15 AM

BUMP

Scott did you ever get this solved?

I JUST chipped my A6 2.7t and have the exact same problems... no issues before being chipped. ABS light and Traction control on in high gears / high RPM under "load" and also

Wednesday, 05 May 2010, 20:52:06
VAG-COM Version: Release 409.1-S
Control Module Part Number: 4B0 907 551 AA
Component and/or Version: 2.7l V6/5VT G01 0001

Software Coding: 06712
Work Shop Code: WSC 26130

Additional Info: WAUED64B91N047196 AUZ7Z0Y1562177
2 Faults Found:

17963 - Charge Pressure: Maximum Limit Exceeded
P1555 - 35-10 - - - Intermittent
16487 - Mass Air Flow Sensor (G70): Signal too High
P0103 - 35-10 - - - Intermittent

Thanks

**gointoscott** · 05-06-2010 10:43 AM

I had it happen also right after getting chipped. What I did to fix it was sent it back to person who chipped it and had them reflash it. I recommend you do the same. The car will not run right and will be a pain if you leave it like this.

On side note. Did you have the MAF sensor code before hand? You may have a faulty MAF sensor. You can check to make sure its plugged in tightly, may try cleaning it, if that dont work you can try running car with MAF unplugged. It will run better but still not correctly. But at least it will be driveable. If MAF is faulty you will probably have to replace it.

The faulty MAF could be throwing the max charge limit too but I dont think so. I personally think they have a few settings set too high and causing it to overboost throwing it in limp mode and cutting it out until you shut it off and turn back on.

If you have the 00 model S4 or early 01's they usually came with the Bosh MAF which were not as reliable and failed. If you had the newer 01's it has the Hitachi MAF and those were better and lasted longer. I have the 01.5 with HItachi and I still am using stock MAF with no problems.

**tuccatucca** · 05-06-2010 02:09 PM

Originally Posted by gointoscott

I had it happen also right after getting chipped. What I did to fix it was sent it back to person who chipped it and had them reflash it. I recommend you do the same. The car will not run right and will be a pain if you leave it like this.

On side note. Did you have the MAF sensor code before hand? You may have a faulty MAF sensor. You can check to make sure its plugged in tightly, may try cleaning it, if that dont work you can try running car with MAF unplugged. It will run better but still not correctly. But at least it will be driveable. If MAF is faulty you will probably have to replace it.

The faulty MAF could be throwing the max charge limit too but I dont think so. I personally think they have a few settings set too high and causing it to overboost throwing it in limp mode and cutting it out until you shut it off and turn back on.

If you have the 00 model S4 or early 01's they usually came with the Bosh MAF which were not as reliable and failed. If you had the newer 01's it has the Hitachi MAF and those were better and lasted longer. I have the 01.5 with HItachi and I still am using stock MAF with no problems.

Our situation seems exactly the same - but I have a 01 A6 2.7T 6spd MT. No, never had a MAF code before and I think my MAF readings used to max out around 220g/sec, now I'm around 266g/sec logged. I have a Hitachi MAF in mine, and I clean it every time I need to take it out, so it should be super clean. Car has 88k miles and I assume it is the original MAF.

This code for me is also usually accompanied with an intermittent 17963 - Charge Pressure: Maximum Limit Exceeded. And the weirdest thing, is that under heavy load and RPM (like 5th/6th gear 4k and above) my ABS and ESP lights come on, and stay on (not flashing).. and will continue to stay on while I am on the throttle. As soon as I let off the throttle and the load / RPMs go down for a couple seconds, the lights come of, get back on it, they come back on. And I am def. not braking traction on the highway at 80, so its not that.

Again all this is only after the APR 91oct chip - before the chip, no issues no codes.

I sent a note to APR to try and sort it out, because when they tried to directport flash it, it bricked the ECU, so they had to send it to APR to be flashed. So really in the end you think the fix is a reflash??

**megafreakindeth** · 05-06-2010 04:49 PM

I had that code when the connector for the maf was broken. this caused a high resistance in the circuit and the ecm translates that to a high intake volume. Ive seen this on alot of b5s where the internals of the connector are broken so the pins can move up and down freely. I think this is why alot of people switch to the hatachi maf because you end up replacing the connector anyways.

**megafreakindeth** · 05-06-2010 04:51 PM

at idle you should be getting about 4-5 grams per second on the maf and at like 2500 you should see about 12-14 grams per second. when i was setting signal too high codes i would be getting about 80 grams per second at 2k. wayyyy too high...just like me

**tuccatucca** · 05-10-2010 09:03 AM

Here are my logs on STOCK mode:

TIME RPM Load Inj. On Time Mass Flow Expected Absolute Pres. Duty Cycle Duty Cycle
STAMP
/min % ms g/s mbar mbar % %
0.01 760 18 2.38 4.14 1010 1010 14.1 85.9
1.41 1440 27.1 3.06 11.58 1010 1010 21.1 78.5
2.82 2080 58.6 6.12 37.86 1010 1050 27 72.7
4.13 3200 65.4 6.46 62 1120 1430 56.6 43
5.47 5440 147.4 16.32 244.64 1500 1620 15.6 84
6.93 4800 100 11.56 158.25 1620 1730 35.2 64.8
8.21 4880 129.3 13.26 182.03 1580 1580 87.5 12.5
9.57 5920 129.3 13.6 220.86 1490 1500 15.6 84.4
11.04 4040 101.5 12.24 136.33 1620 1740 34.4 65.2
12.29 4600 129.3 13.6 171.97 1600 1640 85.5 14.5
13.58 4960 139.1 14.28 202.33 1580 1580 87.1 12.5
14.94 5320 135.3 14.28 208.56 1580 1560 87.1 12.5
16.33 5640 130.8 13.94 216.67 1540 1560 87.5 12.1
17.77 5960 126.3 13.6 218.92 1520 1510 87.5 12.1
19.26 6320 120.3 13.26 219.56 1500 1510 87.5 12.1

91 OCT chipped:

TIME RPM Load Inj. On Time Mass Flow Absolute Pres. Absolute Pres.
STAMP
/min % ms g/s mbar mbar
0 2240 91.7 8.84 63.19 1120 1330
1.22 2480 97.7 9.52 73.78 1380 1430
2.53 2840 109 10.54 91.28 1610 1550
3.73 3240 156.4 18.36 149.72 1630 1750
5.14 3800 157.9 18.36 178.28 2010 2050
6.35 4240 185.7 23.46 227.33 1980 2080
7.62 4680 177.4 22.44 242.06 1940 2040
8.93 5120 171.4 21.76 254.36 1940 1970
10.3 5440 167.7 21.76 265.72 1920 1940
11.71 5800 156.4 20.74 263.14 1860 1900
24.11 5880 154.9 23.8 266.08 1900 1930

Looks a little high... ?

**tdelaive** · 08-16-2012 09:02 AM

had the exact issues, unplugged the MAF sensor and drove home (750Km's), replaced the MAF sensor and the car was still running pretty rough especially at low RPM's.
I checked the hoses and wouldn't ya know it, one of the fat hoses to the intercooler had popped off (we went on a pretty long rough and bumpy ride just prior to the issues)
put it back on and she's never ran better.
love my Allroad, but she's a bit fussy at times.

**alpavel** · 10-18-2012 06:29 PM

My '01 s4 just threw the same p0103 code for MAF high input voltage. The car doesn't climb over 1500 rpm when driving in any gear. Also, the idle stays at 800 for a bit, drops to 500 then climbs to 1300 and back to 800 (when warmed up). I unplugged the MAF and it idles/drives decently, throw's a code for p0102 MAF-low input voltage, but no boost whatsoever. I bought a new Hitachi MAF and it had the same problems as when installed before. The code comes up instantly on start up, even after it has been cleared, and the car idle starts surging instantly when the MAF is plugged in after being taken out. Any ideas/suggestions?