My car's engine light went on with P1647 code, HO2 sensor bank 2 malfunction. I guess it is some short but how can I be sure where that is (and also where the HO2 is) and how can this be fixed, please? What symptoms should I look for as right now I don't see any? In general not too clear what the HO2 sensor is. Please help me if you can. Thank you very much

 

Marcela, I have sent you a separate e-mail detailing things. In short, the sensor is under the air box on the front of the engine. If you remove the filter then remove the 3 or 4 screws holding the air box in place, once the air box is removed, you will see it sticking out of the side of the catalytic converter. Easy to access. As for symptoms, Mona may be running just fine. The computer can use the other side of the engine and get things pretty close to the point that you may not notice anything wrong. You may just be emitting a bit more emissions than is desired.

As for what the HO2 sensor is, the other name for it is the air-fuel mixture sensor. In short, it monitors the exhaust gases for any oxygen. If it senses no oxygen, then it is running the engine too rich and it will admit less fuel to the engine to keep the emissions to a minimum. If it is sensing a lot of oxygen, then it is running the engine too lean and this can be harmful to the engine. It wants to see just a very small amount of oxygen in the exhaust. Odds are, what has happened is there is a heated element inside the sensor that keeps it above the temp of the exhaust. Because of the metal used in the sensor, oxygen tends to cause the metal to cool down. By knowing how much current it takes to keep the sensor a certain number of degrees above the exhaust temp, it knows how much oxygen is in the exhaust. In your case, the most probable cause is the heater has failed and now there is no current able to flow through the heater which the engine computer sees as a problem. The oxygen sensors do wear out over time. They get used under some fairly harsh conditions.

 

Please forgive me for not being able to properly focus on your email explanations. Tomorrow I will try harder including to understand why my engine light (code P1647 detection) came while Mona being parked, not during her trip (engine running). Coincidence? And how can I know if there was too little or too much oxygen? And how did she get the very dangerous for engine too much oxigen if she did? Thank you so much for your detailed explanaton/s. I will give an update after tomorrow's heavy rain stops. Would it help to erase the light before any further verification I will make?

 

Marcela, your problem could very easily be because a critter crawled in under the hood of the car and ate some of the wiring. You would not be the first person to experience something like this.

As for the car getting too much/too little oxygen, I would not worry about that. The computer has a way of monitoring and adjusting things to keep the car safe. So, you are not going to hurt the car by driving it a little bit. Trying to explain it would really toss your mind for a loop. Just understand that the car has the ability to compensate based on other sensors. This is where a trip to a local mechanic is probably in your best interest based on your car abilities. A local shop should be able to take care of you.