finally pulled codes

[ryhi]

ok i got them pulled today and the mechanic said there were 2 things wrong...the first code was the 02 sensor, and the second one was the MAF sensor. he said the MAF sensor might be sending the 02 sensor a bad signal, therefore triggering the 02 sensor code. if i replace the MAF sensor will the 02 sensor be fixed?

[jnolte]

Originally posted by ryhi
ok i got them pulled today and the mechanic said there were 2 things wrong...the first code was the 02 sensor, and the second one was the MAF sensor. he said the MAF sensor might be sending the 02 sensor a bad signal, therefore triggering the 02 sensor code. if i replace the MAF sensor will the 02 sensor be fixed?

not if you have a bad O2 sensor! LOL i would change the cheaper one first which is the 02 sensor, BUT if you have a freind with a good MAS in his w202 then swap him and see what happens.

[moebiusgold]

You need to have it running while hooked up to a scanner. A good scanner will point you to the guilty hardware. There are also lots of codes that contain the words O2 sensor of MAF. Can you be more specfic with their actual No? One thing that I found out was going to different websites gave me slightly different versions for the same No. like EGR fault Vs. Low EGR Flow. In my case that was very telling.
Or if your car has lots of miles you might just replace the O2s and at least clean the MAF. OEM exact replacements aren't so cheap. Good luck, I hate the CEL and I'm an engineer...

[ryhi]

the engine was running... i noticed the brand of the scanner was a snap-on... it had a nice light up LCD....the guy used the circle connecter under my hood and not the one under the steering wheel....

[ryhi]

Originally posted by jnolte
not if you have a bad O2 sensor! LOL i would change the cheaper one first which is the 02 sensor, BUT if you have a freind with a good MAS in his w202 then swap him and see what happens.

oh yeah..i asked him if it was easy to replace if i already had the part and he said it wasnt because my car would have to be connected to a computer for recollaboration or something. is this true? or can i do as u told and try one from another car? i dont think he was trying to get me to bring my car to him to get it fixed because he is a friend's uncle and he even did the scan for free after i offered him money.

[jnolte]

Originally posted by ryhi
oh yeah..i asked him if it was easy to replace if i already had the part and he said it wasnt because my car would have to be connected to a computer for recollaboration or something. is this true? or can i do as u told and try one from another car? i dont think he was trying to get me to bring my car to him to get it fixed because he is a friend's uncle and he even did the scan for free after i offered him money.

You can just switch your MAS easy. Its like easier than filling your car with gas. Just find another w202 with the same MAS part. Switch them. ANd see what happens. then run the codes and see what it says. If it still says the same then you got bad O2 but if it says nothing then it means ur MAS is bad. But make sure you get CEL turned off first before running another test!

[moebiusgold]

If the Snap On Scanner had the S/W for your car he could be right about the parts but I like Jnolte's idea. Your car will recalibrate itself. It might not idle great at first but it will tweak in the long term fuel trims within about 5 starts and full warmups (driving more than 10 Min.).
Using the 38 pin round connector you can look at all sorts of stuff that you can't get to with the OBD II connector. If he knew what he was doing you are going to have to spend some $. I can say that I replaced my O2's even though there were no error codes and wow, what a difference. The members that run their stuff hard seem to thnk that they are a maint. item and should be replaced on a schedule. I had no baseline so I was guessing. My Mass air flow was pretty clean but the temperature probe was covered in an oil film. Didn't make a difference that I could notice.
Good luck. Let us know how it turns out. Stupid CEL.

[ryhi]

a friend that is a mechanic said i might be able to clean it with brake cleaner and an air compressor..... ne1 think its worth trying or has cleaned their MAF sensor n solved the problem?

[moebiusgold]

Lots of members have done that. I squirted the carb cleaner on a q tip, dabbed it on the circut board then blew it off. I don't think that you want to get that stuff on plastic but short term it is OK. I dodn't know the chemical differences between brake cleaner and carb cleaner. What ever you use better not attack the Epoxy conformal coating or you'll be buying a new one. I'd borrow one to try. Takes less than 5 Min. for the swap. Lookat yours and compare the amount of surface conatmination. If it is bad, there is little chance that the O2 could keep up with things. Not knowing the Software, it is possible that it could generate O2 error codes. At one point a previous owner had 8 error codes generated by my cloged up EGR port. It even made a Tranny shift delay error! Good luck!

[ryhi]

after you cleaned urs with a qtip did it solve the problem?

[Denlasoul]

Cleaning the MAS wire can help, but if your MAS is truly bad the only way to fix it is buying a new MAS. You have to test the amount of current running through the wire at certain throttle positions (idle, partial throttle, WOT). I do not know the correct range for your car (unless its a C43), but once you have that info you can test the MAS and determine if you need to replace it.