Air bypass valve FAULT - HELP PLZ.

9516 Views 10 Replies 5 Participants Last post by w203black, Aug 6, 2020

Jonas_Gothenburg

Discussion Starter · Jul 29, 2006

My SLK 230 from 98 has been a trouble maker for a while now. The Kompressor /SC worked fine in the beginning but then I got intermittent faults where I got powerloss in the engine sometimes. Now it is permantent.

I took the car to a MB workshop and they read out the OBD faultcodes for me. It seems like the Air Byopass valve that is mounted in the airfilter box is broken.
The fault code is:
P0803 Component A 16/7 defect

I dissassembeld the filterbox and now have the top lid with the valve house loose. Can I change this unit myself or do I need the reset any values in the ECM and are therfore forced to have it serviced at a proper MB workshop?

Thanks for any help.

BR
Jonas

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Jonas_Gothenburg

Discussion Starter · #2 · Jul 29, 2006

I read all the threads on this issue but I haven't found anyone who actually changed the valve.
For example:
http://www.benzworld.org/forums/r17...tor-air-flap-switchover.html?highlight=bypass

What is the price estimation for this valve?

BR
Jonas

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David in Australia

· #3 · Jul 29, 2006

Part # 111 098 00 09

I would make sure it is not working before replacing ....the valve should close when the kompressor clutch engages....as described in your thread / link

If neither are operating then there could be a control problem...the computer looks at several factors before it decides to turn on the supercharger and activate the bypass

I would only consider replacing the bypass valve unit if you have checked the electrical connection and are sure the valve doesn't close when the clutch engages

I was lucky.....connection to bypass had been inserted upside down at last MB service.........code P0805 recorded..........cheap fix (free)...but lucky find!

Expensive part in Australia ~$A1300......~$US500 in US from my searches....probably cheaper in Europe / Germany if you have a source other than a MB dealer....still an expensive substution if you are not certain it is faulty

Can't be sure, but unlikely the dealer would need to do anything to the ECM

David

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Bazzle

· #4 · Jul 29, 2006

My thoughts only apply to pre 2000 SLK 230 with bypass valve off intercooler.

The only test I know is to rev engine with pipe removed from top and see if it closes as clutch engages.
Ive been suspecting that mine is mal functioning and opening too early.

My Aussie SLK functions differently than USA models. USA models have a boost valve on inlet manifold going to a switchover valve located inside top front engine cover. Boost can also be tapped off that line from manifold. Aussie ones dont have that line.
I have inspected the Airbypass valve on mine and cannot see where it senses boost.
I will in time work it out.

I recon a large bore blow off valve set to 'X" psi might be able to do nearly the same function, not sure yet.

Bazzle

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Bazzle

· #5 · Jul 29, 2006 (Edited)

I have the same fault and am investigating options.
David also has same code he sent to me P0803 with a new Code list (now posted in Sticky above, thanks David)
I have acess to another Airbypass valve I will try to get today. Not sure of its functionality.
I have posted a little bit in link http://www.benzworld.org/forums/r170-slk-class/1272524-slk-230-cheap-power-trick.html

i have also been informed you can just change valve. No reset required just drive learning of Comp

Bazzle

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Jonas_Gothenburg

Discussion Starter · #6 · Jul 30, 2006

Very. very interesting. I will replace my valve body and check if it is behaving as should...I doubt it will.

More info in 24 h.

BR
Jonas

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Bazzle

· #7 · Jul 30, 2006

OK

I changed mine for my spare (maybe faulty too).

Car ran a lot better,was getting intermittant ups and down in power before. Seems to be running OK this afternoon. Will run for a few days.

Put in the Boost gauge again (plumbed into Intercooler intake pipe)
Seemed to be showing boost at about 8lbs.
Occaisonally went to 10?
Will watch it with the other Bypass valve.

removed all codes (P0803) exept P1570!

Bazzle

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Mercedesguy1

· #8 · Aug 5, 2007

Bazzle, is this caused from putting your bigger pulley on?

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Bazzle

· #9 · Aug 5, 2007

Mercedesguy1 said:
Bazzle, is this caused from putting your bigger pulley on?

I would say not.

Changing my valve fixed the issues at the time.

Bazzle

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w203black

· #10 · Aug 5, 2020

Hi. Can somebody show me a photo on where this valve is and how it looks like?

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w203black

· #11 · Aug 6, 2020

Bazzle said:
My thoughts only apply to pre 2000 SLK 230 with bypass valve off intercooler.

The only test I know is to rev engine with pipe removed from top and see if it closes as clutch engages.
Ive been suspecting that mine is mal functioning and opening too early.

My Aussie SLK functions differently than USA models. USA models have a boost valve on inlet manifold going to a switchover valve located inside top front engine cover. Boost can also be tapped off that line from manifold. Aussie ones dont have that line.
I have inspected the Airbypass valve on mine and cannot see where it senses boost.
I will in time work it out.

I recon a large bore blow off valve set to 'X" psi might be able to do nearly the same function, not sure yet.

Bazzle

I have a 2 litre w203. I guess its the same as yours.. One valve from the intercooler? I can't get pressure up as well. I get max 0.4. I have changed this valve already 2 times though as it got stuck completely...

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