code po170, po455 on 97 S320 pls help!! - PeachParts Mercedes-Benz Forum

Cilent1 · #1 05-31-2002, 04:27 PM

Just got car out of shop for brakes and ATF service. Stopped to put gas in the car and hit the freeway to air it out so to speak. First time I really ran the car at sustained high speed. (brief stints of 90 MPH) All was fine till I pulled in garage and the check engine light comes on. Next day had codes pulled and po170, po455 came up. By the way on the way to the shop the fuel level warning light began to flash, manuel says either loose gas cap or fuel leak. Checked cap, nice and tight. Turned car off and restarted, fuel level light stopped blinking. Is this a MAS problem or vacuume leak or something else. Light was reset by mechanic and has not come back on yet (only driven couple hours since code reset) According to posts code 170 seems to point to MAF, but what about code 455 and the blinking fuel level indicator, Is this all related. Thinking about taking to dealer but I'd like to not get hosed!!
Any suggestions before I give myself an ulser!!!
Sorry for long post
Regards - Anthony

stevebfl · #2 05-31-2002, 05:34 PM

The code P0455 is a evap code for large leak. The evap monitor test is run by closing the vent valve and opening the purge valve under precise conditions. A vacuum of up to 25 millibar is pulled and then held. If the 25 millibar can't be reached in a certain time the code P0455 large leak is judged. Possible causes are: large leak and/or malfunctioning tank pressure sensor.

Using the combined codes (the P0170 is a mixture adaption code) suggest a hose being off the purge valve. It is located on the left side of the engine compartment next to the ABS/ASR hydraulic actuator. Right next to it are a couple of switchover valves that change the source to the MAP sensor. I would be sure all these lines are tight.

Cilent1 · #3 05-31-2002, 05:42 PM

Steve I will check the hoses on the purge valve, just getting some facts about what may be going on settled my stomach!! Thanks for the reply

Cilent1 · #4 05-31-2002, 05:55 PM

Steve, just wanted to tell you that I checked where you suggested the purge valve would be and found that a hose was indeed disconnected from the valve.
Even though the check engine light is not currently lit (mechanic reset it) Should I expect it to come back on and then have it reset again or should this remedy the check engine light right away.

Again thanks so much for your insight, if your ever in Orlando drinks are on me!!!

stevebfl · #5 05-31-2002, 06:05 PM

Oh Boy! I'm in Orlando quite often (bg).

You probably don't need to worry about the light if that was the problem. It takes two occurances to set those codes. Any recorded failures will be erased after 40 key cycles (or maybe drive cycles) without any more occurances.