PO300 Code! Let me explain.
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On The Tree
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From: Lehigh Acres, Florida
PO300 Code! Let me explain. Was coming home the other day and went through 2 inches of water on highway at a high rate of speed. Drove the rest of the way home no problem. Next morning I started of to work and the car started running very rough. SES light began flashing. I immediately knew this was a multiple misfire code from previous experience. Let me give you a little info on how poorly it began to run. It began running so badly that while you had the car in drive or reverse I heard what seemed like a very bad clack in motor, but only while car is in gear. Could that be from that cylinder not firing? The moment you put in park or neutral it stops. Sounds strange but I just installed a new higher amp alternator the other day so I decided to double check. I put the car up and inspected belt, bolts, wires and everything checked out. While I was under the car I was inspecting O2 sensors and wiring. Pulled both connectors and the passenger side had visible water in plug. Dried it out and started car everthing seemed good. Today I went to autozone to pick up some shrink tubing to cover the connectors. After running the car and then going inside for a 10 minutes, I came out and started the car and same thing happened. The car ran rough a until the car warmed up a bit and it quit. Went back and had them put it on scanner and it was infact a PO300 code. What puzzles me is it will do this after startup for only a few minutes and then the car runs fine. Shut it off five or ten minutes and it will do it again just for a few moments. I have not yet checked plugs, but if the O2 connector did get wet and or fried, this should foul the plugs right?
Thread Starter
On The Tree
iTrader: (4)
Joined: Feb 2005
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From: Lehigh Acres, Florida
Swapped Passenger side O2 with the rears. The rears are just being used as bungs. Drove car and it started again. Got back under and noticed that the A/C condensor is dripping right down over the header at the o2. Checked plug and again it looked like some more water had got into the connector. Dried it out and started car. It started stumbling again, light flashed and stayed on. I went to Autozone to get a new O2 and also to have it scanned one more time. It was the PO300 code again. When I left the light went out and began to run fine.When I got home I installed the new O2 and so far it has not acted up. I mean what would be the chance that the O2 I was using as just a bung was also no good?
Last edited by frack; Sep 9, 2010 at 09:38 AM.
i would be willing to bet you fried your MAF with the water. same thing happened to me (drove through water) an i fought it forever. after new plugs, o2's an hours of head scratching it still wasnt fixed. put a new maf in an no problems since.
It could be the MAF, but you also may have managed to fry a plug/wire/coil. Is the only code you're getting P0300? Because I believe that P0301 - P0308 are designated misfire codes relating to which cylinder is having the issue. So if you're also getting any of those codes I would start looking there.
