Designer17

about a month ago, my car stopped shifting into overdrive so I had it checked out and turned out to be a couple bad coil packs, one of them being cylinder 2 and not sure about the other. I had it fixed and it ran great for about a week. It started bogging down, loosing power and the gas mileage started to decrease again. I put my scan tool on it and it showed it was just an 02 sensor fault, so I wasn't too worried. A couple weeks went by and it started running worse than it ever has. I now have to press the gas peddle to the floor in order to get up to 30mph. It bogs down for a bit then shoots up to speed then bogs down over and over again. Its running very sluggish and choppy. I put my scan to on it this morning and now its throwing a ton of codes.

P0300-random/multiple cylinder misfire
P0302-Cylinder 2 misfire
P0304-Cylinder 4 misfire
P0306-Cylinder 6 misfire
P0172-System too rich(bank 1)
P0141-02 sensor heater circuit(bank 1 Sensor 2)

My question is, what could cause all these codes? I'm assuming/hoping its all related to one single issue and not 6 separate problems. I should also note that a couple years ago the exhaust system from the headers back had been completely replaced along with the mass air flow sensor. I know its hard to diagnose the problem over the internet but any help will be greatly appreciated.

Thanks,

Aaron

Baetke

I'd guess a bad oil control valve on Bank 2.

hypervish

I'd reset the codes, and see which code pops up first. And, then use that first code to diagnose and find out what to do next.

Designer17

So, I reset the codes before my ride home from work yesterday and my car appears to be running fine now. I ran another scan on my way into work today and the only code its showing is the 02 sensor code mentioned in my first post.

Is it possible that the faulty 02 sensor is the cause of all the problems I was having? I've been getting that 02 sensor code for years and never had any issues until now.

Baetke

The P0141 is indicating a faulty heater circuit on the O2 sensor after the cat. The only purpose of this sensor is to tell you if your cat is working efficiently. I would have nothing to do with the other codes.

If your car starts to run crappy again, notice if the brake pedal pressure is higher than normal when you try to stop. This would point you toward an OCV problem.

The P0300 is just a result of the P0302,4,6 codes.

Can you pull freeze frame data with your scan tool?