I bought the universal code reader from Harbor freight ($39.99), item # 46030. I tried reading a check engine situation on a 1996 SL320. It was unable to pull the code. Then i tried with an Actron 9135 and it read the error code (P0441). Harbor Freight tech support told me that their reader can only read universal or generic OBDII. Not sure why the Actron (non proprietary) would work but not the HF one.

I am looking into the Actron CP9145 which also allows reading live streaming data. I might buy that one.

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1972 450SL
1982 300D Turbo

My 96 SL320 gave me the same code, it is purge flow pressure. I replaced the purge valve and the check engine light has never came on again. (6 months) With the MBCA discount I got my new Purge valve for $96 at the dealer. Shop around, they are not cheap. Good luck!
Brian

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Brian W. Heitman

www.MBCA.org/northtexas

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Thanks for that info brian. Would there be any harm in not replacing the purge valve?

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1972 450SL
1982 300D Turbo

Well,
with my car I didn't have a code reader at first, and when the engine light would come on I would disconnect the battery and reset. I finally saved my pennies (got permission ha ha) and bought a scanner. I drove it that way for about a year because I didn't know what was wrong. The P0441 code just says it is incorrect purge flow pressure, so when I got the code I checked everything in that system, It could be a vacuum leak or loose hose, bad gas tank cap etc.. All of these things contribute to the problem. I tested my purge valve and it would not even click, they are supposed to make a clicking noise when activated, I just put 12 volts to it and nothing happened. I then knew that the purge valve was bad. I don't think it will hurt the car to drive it, however you should be extra careful of the pressure in the tank, and it may use more fuel since the purge valve opens and allows the intake vacuum to pull gas fumes from the charcoal cannister to burn in the engine, without it you are not getting the use of your fumes. This is basically an emission system so that you don't expel gas fumes into the air, rather burn them up in the engine and through the catalyst minimizing the pollution, so it will probably be ok that way, but here in Texas my car would not pass inspection unless it was repaired. The purge valve is electrically operated and is located in front of the ABS pump, it has a line coming from the firewall, (Charcoal cannister in trunk on 129) and then a line going to the intake manifold, both black plastic, and the valve itself says "MOT with an arrow pointing to the motor output side" Happy Benzing!
Brian

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Brian W. Heitman

www.MBCA.org/northtexas

Join MBCA!!!

Oh,
I have posted the system function and locations here http://www.mbca.org/northtexas/vacuum_pneumatic.htm

Take a look, you will see where everything is located and know where to look to check it out. I hope this helps.
Best Regards,
Brian

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Brian W. Heitman

www.MBCA.org/northtexas

Join MBCA!!!

Purge valves are easily cleaned with WD40. I also squirt some in the hoses and let the vacuum suck it through the valve..
If the valve is funtioning , you can feel the frequency beats with the valve in your hand . They just get dirty from fuel emiisions and stick open/closed.
If stuck closed , they do not allow flow, but if they stick open, then they create an internal vac leak and will raise hell with fuel trims. Many an unfound vac leak is simply a stuck open purge valve..

They use a rapid on/off feature so the engine does not read lean/rich by gulping all the air at one cycle. It should come on after 70C.............