Just yesterday going home from work I noticed my car was rough idling and low power. Luckily I was able to make it home. Read the codes I got p0300(random misfires), p0301(misfire at cylinder 1), and p0137(o2 sensor bank 1, sensor 2). I currently have 125k miles and I replaced all spark plugs with iridium ones at 100k. I physically inspected the spark plugs and they look good. Based on this I figured I probably have a bad ignition coil so I went ahead and just bought a new one I replaced ignition coil at cylinder 1 and still same outcome. I'm going to do further troubleshooting to see I can figure this out. Just posted here to see if anyone had similar codes and what you did to fix the issue. Is it possible that a bad o2 sensor(bank 1, sensor 2) could cause misfiring or did the misfiring code(p0300 and p0301) triggered the p0137 code?
No, the B1S2 oxygen sensor is not going to cause an engine misfire. Its purpose is to allow the engine ECU to monitor the condition of the catalytic converter. The fact that the oxygen sensor is producing a low voltage is indicative that the air/fuel ratio is too lean. That, combined with the P0301 code would imply that the cylinder 1 fuel injector may be clogged. By the way, I hope you agree that cylinder 1 is closest to the passenger-side fender. Odometer reading?
I have 125k on the odometer and yes cylinder 1 is on the passenger side. Thanks for the info regarding the o2 sensor most likely the original p0300, p0301 codes triggered the o2 fault. Anyway I ran some additional tests earlier today. I found that all ignition coils and spark plugs are working fine. I also reset my error codes and drove around a little bit. This time I discovered I now have codes p0300, p301, p302, and p304. I'm going to look at the fuel injectors next. Is there anyway to test the fuel injectors without totally removing them?
No. However it would be unusual for three injectors to fail at once unless you got some bad gasoline. You might consider first measuring the fuel line pressure which should be 44-50 psi at engine idle. If you are interested to do that, I recommend you obtain the factory repair manual info at techinfo.toyota.com so that you can see what is involved in hooking up a fuel pressure gauge. If you find the fuel pressure is low then you would have to replace the fuel tank (as the fuel pump is located inside.)
Only way is to pinpoint your problem... To have Techstream on your car and make ride to record various information and look for imbalance from healthy engine... There could be just fuel or something else Posted via the PriusChat mobile app.
Just an update guys. I discovered I have a bad fuel injector at cylinder 1 by doing a resistance check. After replacing the injector car now runs great. I still find it strange that it triggered misfire codes for the other cylinders though.
I am having the exact same errors.2008, 270 k on odometer. Changed spark plugs, fuel injectors, coils, pcv valve and map sensor. Wondering what to check next.
