Hello friends,
I am new to this forum and have been learning some great information. I have an issue and wanted to get your help/guidance before continuing to pour money into it.

Here is the info with the kind of timeline....

Check Engine light came on... took car to autozone... was told error code is P0442..... changed gas cap (got from MB dealer).... got code reset by an autoshop.... drop around.... Check engine light came back again.....

Went to the autoshop that works on domestics and imports.... got oil changed ($125)... when can is even and i check engine oil, it says "Perf. Service on time" but while driving the screen becomes red with a beep and says reduce engine oil level (something like this)... does it mean the shop added too much oil? how much does the 2002 C240 take? this is one error...

For check engine light, P0442, the shop changed purge control valve and canister shut off valve and reset the code.... cost $600 (included smog test, parts & labor).....

Drove around and check engine light came back on... this time code is P0446.... took it back to the autoshop and they told me that this code means that now they have to change the fuel tank pressure sensor... it will cost around 250-300 for part & labor... before i go and spend this money, just wanted to get your opinion if this makes sense and i should continue with this repair.... i need to get the inspection done and cant get it done.

why would P0446 not show up in the first place when P0442 was showing up? is this something that might have been messed up by the autoshop? please guide/advise on what should be the next steps.

sorry for the long post but i wanted to communicate as much information as possible. Thank you all for your time...

Regards...

P0442 means the Purge control system has slight leak. Leak can be in the hose connection or shutoff valve of activated charcoal canister.

P0446 means the Activated charcoal canister shut-off valve is defective.

Maybe there were more codes but the mechanic thought the main issue was the 442 and if he repaired it the 446 would go away. These codes are similar so one code might cause the other one to go off even though the other was is fine.

Sounds right, just have them fix it.

Here is a picture of the unit.

yes you need to reduce the amount of oil you can suck some out from where the oil dipstick tube is (or better yet get the shop to they dd it)

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Thanks so for P0446, they want to replace Fuel Tank Pressure Sensor. Does that sound right?

so should i let them change the tank pressure sensor for code P0446? thanks

Ask them about it. Tell them that the P0446 P0446 means the Activated charcoal canister shut-off valve is defective. And see what they say. They might know more than me. I'm not a mercedes tech but I did stay at a holiday inn

Print the post I made and take it to them. See what they say.

Good Luck and also tell them about the extra oil. If you set your car in "Dyno Mode" you should be able to see the oil level. See how much extra is in there. 1quart and above is bad and I would have them suck the oil out with an oil extractor.

so went back to the shop to get the shut off valve replaced (P0446) and they took the part to dealership to replace.. Dealership refused to return the part. they want the part in the car and then they want the car in their shop to check. if the part is the issue, they will replace it otherwise they will charge $130 for diagnostics..... anything wrong with this picture? how will i know if that part was the issue or not..... hmm thats why everyone calls them stealership


now i will have to take to the dealership next week.