[ALephart]

The P0803 DTC reared it's ugly head today. Before reseting it this time I took off the hose that goes to the throttlebody on the airbox and revved the motor. The butterfly sat lifeless. I then reset the DTC and repeated reving it and it moved! I still have no idea why the computer reports it as a 1-4 shift solenoid malfuntion but I think I am getting close. Any further ideas?

Aaron Lephart

 

[Bazzle]

I used to get the same code.
Had to change the airvalve on the Aircleaner box,,, no fault since..
(touch wood)

Bazzle

 

[ALephart]

I bought and installed a new airvalve today. Sadly the DTC returned. Any other ideas?

Aaron Lephart

 

[Bazzle]

I gave you a Bum steer, for that code I think I reset the Auto trans adaption using Carsoft.

See we are humans on here after all

Bazzle :surrender:

 

[ALephart]

Could'nt I just command the solenoid manually using a scan tool?

Aaron Lephart

 

[ALephart]

I took it to a shop and had them try and manually trigger the solenoid. They confirm it works only some of the time. $30.00 part later I hope it fixes it! I will know more on Monday.

Aaron Lephart

 

[Bazzle]

See if you can the info on how they change it? May be an at home fix.

Bazzle

 

[ALephart]

I'll check. Supposidly all that is required is dropping the valvebody located in the trans pan area and replace it.

Aaron Lephart

 

[David in Australia]

Aaron.............I don't think Bazzle did give you a 'Bum Steer'........but I think you are now on the wrong track............the P0803 upshift code is generic......the MB Code for P0803 is Component A 16/7 defect.....this is the air bypass valve (ABV) you checked in your initial post.....................

Your ABV may not be faulty, but the control or connections may be faulty.......this could explain the code persistence and the fact that the valve worked after the code was cleared.........

If the performance combo of the ABV, kompressor clutch and cam adjusting magnet are not working then there is a very obvious lack of power........

In my case it was the electrical connection at the ABV.....very easy fix.....but I understand the famous K40 relay is also involved with this combo.............

Bazzle..........if you disconnect the ABV electrical connector and then do a Carsoft scan I think you will get a P0803 code......................I can double check this ....but this is what I can remember from last year when I was investigating these things............

http://www.benzworld.org/forums/r170-slk-class/1272548-air-bypass-valve-fault-help-plz.html


Cheers

David

 

[ALephart]

Just got a call from the shop, it WAS'NT the solenoid. It's not the EGS, but rather whatever controls that. They had a new EGS and tried that but it performed the same. Now they are literally going wire by wire to find the problem. I did'nt know this car used a C.A.N. system bus, pretty advanced for 1998!

Aaron Lephart