Hi Prius chat experts! I have had so much help from you with my car, so here goes another. My check engine light came on the other day, with no symptoms or problems. Today I stopped at the Auto Parts store and had the codes read. They were P0440, P0441, P0446, and P0301. They are for the EVAP system and misfire. I had read here that one of the codes could be for the gas cap so I tightened it and then, also as read on here, disconnected the negative 12 V battery cable to perhaps clear the check engine light. I was curious. Aargh! When I started the car again, I now have not only the check engine light, but the red triangle exclamation point. How would you proceed? The 12 volt battery is around 5 years old. The entire exhaust system was replaced last year.(not O2 sensors though) The hybrid battery was replaced at 70,000 miles and I now have 110,000 miles on it. I really wonder why disconnecting the battery and reconnecting it caused more error lights to appear? Also, the Auto parts guy said his code reader was fine for my car but I seem to remember here that there may be a special Prius one. Thanks for whatever help you can offer.
Don't worry about the master warning red triangle warning light. Worry first about DTC P0301 which means a misfire on cylinder 1. Usually this is because of a bad iridium spark plug or a failing fuel injector. When were the spark plugs last changed? Get Mini VCI so that you can retrieve the DTC yourself.
Thanks for the reply, Patrick. The spark plugs were changed this past summer. Is it possible that one went bad? The old ones did not really look like they were too worn. Funny, when I started my car this morning, there were no warning lights on. I then remembered that when I installed a new 12 volt battery it took a few starts for warning lights to go out. Is there a way to check for a "failing fuel injector? Can this misfire have something to do with the oil being too full?
It is possible that water may have dripped onto the engine valve cover and gotten into the spark plug well for cylinder #1 which is closest to the passenger fender. The spark plug should be removed and examined. The spark igniter also should be examined for flaws such as a crack, burn marks, or rust deposited on the plastic body. When a new 12V battery is installed, there is normally a period of time when the ECUs are powered down because it takes some time to remove the old battery and install the new. During that time, any DTC previously logged by the ECUs would be erased. There should be no warning lights on when the power is restored and the Prius is made READY, if nothing is wrong with the car at that time. A professional mechanic should check the fuel injectors as they are not easy to remove. If the engine oil level is too high, that should be corrected by draining out sufficient oil to bring the level on the dipstick to the top dimple. That issue should not contribute to the engine misfire. Good luck, figuring out the engine misfire issue.
Thanks. I will have the spark plug and injectors checked. Would correcting this (if it is indeed the problem) also correct the other codes for the EVAP system?
There are 'injector cleaners' but read the labels and make sure they are catalytic converter safe. No guarantee but often cheaper than a mechanic and it might work. Usually the same fluid that 'cleans the throttle body and plate' is also an injector cleaner. After making sure there is no sticky throttle plate, the rest goes in the tank. That does not mean it did any good but so far, no harm. Bob Wilson
When's last time both injector seals were changed? Easy for DIY and not very much if parts ordered online.
This is a zombie thread, skyway. However, since you raised it to the top again, I'd comment on Beth's question - why is my oil level too high? In my diesel trucks, that is a bad sign. Usually means that an injector tip has broken off - one common cause is water in the fuel/bad gas. When the tip breaks, it dumps fuel in the cylinder, which drains past the piston rings and into the crankcase raising the oil level. Shortly thereafter, the engine will hydrolock, maybe (IDK) when there's no more room for the fuel to drain. Not the worse thing if you realize what's happened and don't keep trying to get it to start. Not sure what happens with these cars since there's no starter; but on the trucks, you can bend pushrods. And on the diesels, the engine can "run away," i.e run on its own feeding off the fuel in the crankcase. I've had it happen twice, and it is scary as heck.
