New tune new MAP sensor 16490 code.

I just upgraded my injectors set the I/Q to 5 via hammer mod, got my tune upgraded from stg2 to stg4 And installed a new 3 bar MAP. Im now getting 16490 codes. It won't produce any boost with the 3 bar map and won't rev over 2500.
If I pug in my old (stock) 2.5 bar map (outside of the intercooler)I get no codes. If plug in the 3 bar map when not mounted in the intercooler I still get the code. I have not tried to install 2.5 map to if it will produce boost.
Is there a measuring block in VAG COM to look what the map voltage is?
I did the n75 test and the actuator arm on the turbo moves about 3/4" of an inch.
I'm assuming one of 2 things. I've got a bad (new) 3 bar MAP or the tuner forgot to set the tune for a 3 bar map.

Actually, the first thing to do is to plug the 2.5bar sensor back into the manifold and go for a test drive to see if you get any more codes and go from there. I hate to ask, but where did you get the new MAP sensor from? If you get the implausible signal error as soon as plug the sensor in w/o the engine running, then it is likely the sensor. BUT, I suggest you reinstall the 2.5 map sensor and run logs in Group 11 to check the actual vs requested boost as a reference point from which to work from.

The sensor is a Bosch unit from one of the forms reputable vendors. She I first started it up I got the alarm code. I noticed that it wasn’t completely plug in. It plug it in fully butbstill got the code. Is it possible I fryed the new map? I’ll do test logs later 2nite and see how they look. Does anyone know how much they are at the stealership?

MAP sensors are electricaly all the same:

G71/G72 - Manifold Absolute Pressure (MAP) Sensor
1 BR/BL Engine Control Unit ( Ground )
2 GY/GN Engine Control Unit ( Temperature output, Variable Resistance )
3 LI/R Engine Control Unit ( 5V input from ECU )
4 Y/BK Engine Control Unit ( Pressure output, 0.5 to 4.5V )

Here's some "only had one coffee" math:

More or less (as they aren't 100% linear) 500mV is 0 mbar and 4500mV is 3000mbar on a 3 bar MAP sensor. 3000 input units to 4000 output units with a base of 0.5V works out to: 500 + 1.333 x input mbar = output millivolt.

That means with the engine not running, and key on you should have about:
500 + 1.333 x 1000 = 1833 millivolt or 1.8V

At 25 PSI boost (1700mbar over ambient):
500 + 1.333 x 2700 = 4099 millivolts or 4.1V

I don't know if any of the "bad" 3 bar MAP sensors are still around: some time back there were some that were that the reputable vendors sold. How do I know, I had purchased one.


First thing look at the holes in the MAP sensor there is an aluminum insert where the screws go through. If the pressed in "ring" has a slot in it, it should be the genuine article if there is no slot, then it is a knock off. Even though MAP sensors almost never fail, they do fail and sometimes come out of the box bad.

When you plug the 3 bar sensor into the harness clip is it rock solidly connected or will it slide apart without using the release lever?

thanks for the reply's.

Nevada I just found an old post you had where you talked about the bad sensors. I did buy this one about a year or two ago and its been sitting on the shelf waiting until I finally got my upgrades for it. it has no slot and takes some work to get it to click in the plug. I noticed that group 10 shows with key on only, baro and actual as exactly the same number. The 2.5 bar sensor shows about a 100mbar difference.

I put the 2.5 bar back in and I get boost. although It seems to be limited to about 19-20 psi on my gage and is drivable. it does show 2601 (max) specified and requested for group 11. I wonder if that is limited by the 2.5bar sensor. I would hope that 3 the bar will allow it to go higher. I did get a stg 4 25 psi after all.

Does the 2601 mbar come out to 23psi? I f so I may have a boost leak somewhere or my gage is off. I'm waiting to hear back from my tuner to see what they think about the situation. I'm going to order a new 3 bar sensor tonight anyway and see what happens.

Hasenwerk, do you know if there is measuring block in VAG-com that you can see the actual voltage or do just have to do the math and use group11 to compare to?

either way I'm going to compare your numbers once I get a new 3 bar sensor.

DI Fan stop wasting your time. If it has no slot it is junk. Get the replacement installed and all should be well from that point forward.
Here is your answer: 2601 is 23.22 PSI



(Wow, somebody did read my old posts, LOL)

Isn't 2601 the original scaled limiter in the ECU?, I have a VW T5 2.5PD and they have a 3bar MAP sensor as standard but when you do data logs they stop reading at 2601 mbar even though it's a 3000 mbar sensor.
Tuners over here either re-do the limiter so they actually read 3000 mbar or they just fit and scale for a 4 bar MAP sensor.

I got about 23psi with my math too. I hope the 3 bar sensor will make things all good. It will be here tomorrow. Would the ecu somehow get limited to 2601 due to running the 2.5 bar map? We will see what happens.

I will say, even running the 2.5 bar map stg4 with 1019s. Is great to drive.

Should I be getting more smoke by only running 2.5map? Because there is only lite haze at WOT like my last tune. I wonder if more measured boost will somehow bring more fuel. I’ll have to look at the fueling after I install the new 3 bar.

Is the tune MAF based, or MAP based, or did you ask?

Running the 2.5 bar sensor in a 3 bar tune will end up with you getting less boost.



Basically a 2.5 bar of pressure it will be giving out 5v's. But the ecu thinks 5v's is 3 bar. So the ecu will be controlling boost down - by a factor of around 1.3 so that should get you to your 25psi.


The 2601 just shows the tuner is a bit lazy and didn't bother doing the software updates to you can read correctly in vcds.

DI fan said:

Hasenwerk, do you know if there is measuring block in VAG-com that you can see the actual voltage or do just have to do the math and use group11 to compare to?

either way I'm going to compare your numbers once I get a new 3 bar sensor.

Click to expand...

I don't think VCDS shows voltage. I would use a multimeter on the #4 wire.

Here is a different math version of boost using a 2.5 vs. a 3.0 bar Map sensor. If your tune does not throw an immediate error--some do not--putting a 3 bar MAP sensor on a 2.5 bar tune your boost will increase by 20%. Why is this? Because 0.5 is 20% of 2.5 so a 3 bar MAP sensor will "scale" about 20% more boost. The 1.3 factor mentioned above might be correct when going the other way from using a 2.5 on a 3 bar MAP tune.

I'd used 30% as the bottom end of the map sensor is not 0mbar normally it is ~ 500mbar. So 2500-500 = 2000 mbar working range. 500 mbar is therefore 25% of the working range.



However I think I got it wrong last night and used atmospheric pressure 1000mbar instead of 500mbar as the bottom end of the sensor so ended up thinking it was closer to 30%.

Nevada_TDI said:

Here is a different math version of boost using a 2.5 vs. a 3.0 bar Map sensor. If your tune does not throw an immediate error--some do not--putting a 3 bar MAP sensor on a 2.5 bar tune your boost will increase by 20%. Why is this? Because 0.5 is 20% of 2.5 so a 3 bar MAP sensor will "scale" about 20% more boost. The 1.3 factor mentioned above might be correct when going the other way from using a 2.5 on a 3 bar MAP tune.

Click to expand...

You need to add some fuzzy logic here! If you put a 3.0 in place of a 2.5 bar MAP it isn't 20% more boost across the board - only at the top of the scale. It's the high number that changes and not the bottom number! So at 4.5V output, the 3 bar is at 3000mbar and 2.5 is at 2500mbar (actually 2600!), so 120%. However, at 0.5V both are at the same pressure which is basically to zero and that's "no change". At 1000mbar the difference would be around 7%

My new 3 bar map fixed the issues. Yes the new one has the slots in the metal inserts. And does not throw any codes. Thanks for the help all. Now I just need to dial in the fine details of the new tune and nozzles....... Dial in IQ for light haze at WOT and figure out max RPM.

My old tune went to 5200. With the new tune I've been shifting for test purposes at 5500. It may go higher but my tach only goes to 5500. I'll have to use vag-com to figure it out. I suppose I could ask my tuner.

DI fan said:

My new 3 bar map fixed the issues. Yes the new one has the slots in the metal inserts. And does not throw any codes. Thanks for the help all. Now I just need to dial in the fine details of the new tune and nozzles....... Dial in IQ for light haze at WOT and figure out max RPM.

My old tune went to 5200. With the new tune I've been shifting for test purposes at 5500. It may go higher but my tach only goes to 5500. I'll have to use vag-com to figure it out. I suppose I could ask my tuner.

Click to expand...

Had a bunch of customers who purchased from a bad batch of 3 bar map sensors a while back from reputable vendors (worldpac or such). They would split in two, and fail, leaking. I got so many calls from PO'd customers complaining about the tune. The pressed in aluminum spacer is the give-away of counterfeit part.

Glad you figured it out. I don't recommend running it out past 5k unless you have upgraded your rods and pistons, and head studs. Your tune has both maf and mafless running capability, and probably has some other goodies like "LFB", and Launch control. It must go like a Rocket now!!!
Jeff ;-))