mbcrazy

hi,anybody knows what check engine code po170 stands for?please let me know thank you.

brett san diego

Google is your friend...

http://www.obdii.com/codes.html

It refers to "fuel trim malfunction," but doesn't say what kind of malfunction. Need more info to know what to do with that fault code.

Brett

jaamb85

I am having the same Error code with my car this week. First I thought it was my gas cap. Then, my mechanic thought it could be a few different things.... Fuel injection, air intake leak, engine wear, and something to do with pressure. He checked through everything and cleaned out the air intake and sent me home to keep an eye on things. A day later the error message is on again. He said it was something to do with pressure that could be the last thing on the list. On my receipt he wrote the error code PO170 and then FUEL TRIM.

My car drives wonderfully. It actually drives smoother and seems to have a little more power on the highway since he cleaned the air intake. I am not really sure what is wrong with it. I am trying to gather more information about this error code. Hopefully I can just fix it myself.

Jason

bicylindrico

This is most likely the airflow sensor on the ME injection system. It is a known problem and effects all the cars with this injection system. The other possibility is a small vacuum leak. This would include a disconnected vacuum line or malfunctioning control part like a purge valve etc.

Your technician should be well aware of this fault code. He could reset the ME adaptation values and see if the engine runs very lean at high load conditions. This is almost always caused by the airflow sensor failing. The ME continually tries to adapt to this failing part until it reaches the end of it's ability to do so. That is what the fault dictates. I hope this helps.

jaamb85

My mechanic plugged the car up to his Star Diagnosis yesterday. The car isn't running rich and he said something about a spike after reving the engine. I don't know exactly.
He seems to think it's either the MAF or the Fuel Pressure Regulator. He is leaning towards the FPR. I am also getting a couple miles per gallon less for fuel economy...The again the weather is warming up too. I have noticed a gas smell towards the front of my car after parking it.
The check engine light came back on shortly after accelerating agressively around 4000 RPM.

This upcoming wednesday I have an appointment to do further diagnosis. I guess I'll have him test the fuel pressure regulator first... Then test the MAF. I am hoping for the FPR to be bad since it's about 1/3 as much.

Any information is appreciated!

Jason

bicylindrico

The gas smell would be my first place to start. That is very abnormal. A failing airflow sensor will cause a lean condition and poor power at higher RPM's. The regulator could cause the fault code, reduction in mileage(due to increased rail pressure) and possible smell if leaking externally.

I also ran across a couple cars that people would overfill the tanks and saturate the charcoal canister. The purge system would then suck the excess fuel and cause a number of problems. You would know if you are a "nozzle pumper."

Your tech could look at the adaptation data and tell if it's a lean or rich condition causing the check engine lamp. This should give you some direction. Have you made any changes or repairs to the car recently?

jaamb85

yes. Recently the car had a tune up. Plugs, wires, one coil, A/C blower motor regulator. hmmm. Fresh oil changes and new filters. That's about it for the past year.

I went to AutoZone today to have the codes read. I wanted to see them myself. Sure enough it's just one code... PO170. In the guy's little book of code explainations he found a list that also included an O2 sensor as well as fuel injection and a few other things. I bought some Techron to clean the injectors. The code was erased and I've driven about 10 miles and nothing has come on.

bicylindrico

You have to understand that code readers of the generic variety can only read the codes the feds say have to be accessible. They are the PO codes you speak of. The Star Diagnosis will give you MUCH more information than anyone else can outside of the dealership. The adaptation data will help to understand if it's a lean or rich problem. That makes a huge difference in trying to "guess" what's wrong. You need to have all the info you can get and then start looking for answers. PO170 alone is not enough.

If you intend to own a Benz for any length of time I recommend you find a friend at the dealer. I don't mean any ill will to the independents, they are just limited to at least some degree on the abilty to access needed tools and information. You need to have access to this equiptment when these problems occur. But then again the tools are only as useful as the tech using them. Be sure to find a good tech at the dealer and this problem should be much more visible in an hours time. Get a flunky and it turns into thousands.