So i have a 1997 audi a4 aeb 1.8t, bt with eurodyne 830cc tune.

So i have to pass emmisions and my B1 S1 is throwing a low voltage code.
These are the codes i pulled from vag com
18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 - - - Intermittent

16515 - Oxygen (Lambda) Sensor B1 S1: Signal too Low
P0131 - 35-00 - -


I went ahead and ordered a new 02 sensor and after replacing it nothing changed. So i traced the wiring and everything seemed fine.
When i got into the ecu box, this is what i found.

Quite a bit of moisture and water.





I'm starting to consider that it could possibly be the ecu.
The only other problem i have with this car is the battery is shot, so i have to jump it to start it if it sits for over a day.


Let me know if you guys have any conclusions because i am stumped.
Maybe it is possibly the tune also?

If i clear the codes the 02 cel will return within 5 mins, and the power supply is more irregular.

 

Dry out the ECU and box, hit the connection points with electrical contact cleaner, and then try it again. Get the water out of there first and it may be easier to troubleshoot.

 

Ok, I cleaned the battery grounds and the valve cover and the 3 under the coolant reservoir.
Cleaned all the contacts on maf, ecu, 02 sensors.
I cleaned the maf sensor.
I also dried out the ecu. The light still came back for the sensor.
After hooking the sensor back up I noticed how resistant it was to clicking in.
Partly because it was a rear sensor I used to I had to do some filing down to get it to plug in to the primary.

I am going to try and trim it better so it will click in better to see if that may fix it.
I'll post back in the morning to see if that fixes it.

 

Just to clarify, I didn't file down the actual sensor, but the plastic part where the sensor plugs into the harness.

There's a notch that is unique to first sensor and the second, and to my understanding the sensors are the exact same after researching.
So I filed down the notch on the plastic part so that it would connect.
And I am assuming that it could use more filing to click in further.

 

Does anyone know if your supposed calibrate the new o2 sensors?
If so, what is the procedure for a narrow band sensor.

 

Ok, so i fixed the connection with the sensor and it clips in completely now.
i also tried calibrating it like you would on a wideband.
Still no luck.
Also it simply throws the code idling in my driveway, i do not even drive it.

While I was running it I tapped the throttle to see a little poof of smoke come out of the clamp on the exhaust, i tightened the clamp on the exhaust down to about 50ft lbs. and you can still see some gasses coming out in this vid after tightening it.




And here is where my 02 sensor is in location to that clamp.
eCBIFl.jpg?1

And a little moisture at the manifold to turbo, but its been doing that for some time now.

 

When you say you "dried out the ECU" what exactly did you do? If it were me I would open the metal casing, make sure it is bone dry, then clean anything that looks corroded with contact cleaner including anything internal and any external connections..

If you keep getting the code and you have replaced the O2 sensor, the next step is probably to measure the resistance from the pins at the ECU connector to the pins at the 02 sensor, if there is little resistance than your ECU was probably damaged internally.

You should double check the O2 sensor you replaced it with will in fact work, I would guess that it does but I don't know for sure.

 

Here is the resistance i pulled at the connector.

KwMYUl.jpg?1
Y3fO0l.jpg?1



Im going to heat the sensor and then read the male pins.

 

I measured the sensor, and it came up with 2.5 resistance.

I swapped the pre cat sensor into the post cat connector, and the post cat sensor into the pre cat connector.

And it still pulled the code for b1 s1 low signal.

 

I think its gonna be something related to the relay. But i have no idea how to find it.

Refering to this post
http://forums.vwvortex.com/showthrea...Signal-too-Low


Either that or the ecu needs to be replaced.