Several problems after alternator died and replaced
 

Hi,

I have a 2008 Odyssey (EX or EX-L, I bought it used, so not sure exactly) at 130K+ miles.

Several days ago, while in Yellowstone NP, the alternator died. First I noticed the battery voltage dropped to 10V, then gradually to 9.8V and eventually the whole car completely shutdown. We were able to drive for about 5-10 miles when I started to notice the battery voltage dropping.

After the alternator was replaced by a garage, and after I drive it for a one or two days, it starts to show several engine error codes.
I got 5 error codes using my ODBII reader:

• P0404 Exhaust Gas Recirculation Control Circuit Range / Performance
• P0301 Cylinder 1 Misfire Detected
• C0300 Manufacturer control (from this website: C0300: Code Meaning, Causes, Symptoms, & Tech Notes (engine-codes.com), it seems the error code mean: Rear Propshaft Speed Sensor)
• C1555 Manufacturer control (from this website, it looks like the code means: 1 - Fuel and Air Metering 5 - Fuel Composition Sensor Circuit Malfunction, 5 - Cylinder 1 Injector Circuit Low 5 - Crankshaft Position Sensor B Circuit Malfunction)

C1555 appear twice in the ODBII reader, so total there are 5 error codes.

Another thing is VSA light stays on. Not always, but it has a high chance. If it stays on, it stays on for the whole time until the car is turned off. Or it may behave normally after the car is turned on for the whole trip (i.e. until the car is turned off).

What I can feel about the car is, it kind of "shakes" when idling. And sometime it is very hard to start the engine. Not all the time, sometime only, like the engine is very reluctant to crank. Once everything is running it appears fine in general. just gear shifting feels a bit more noticeable than before.

I kind of feel that all these errors could be caused by one common root cause, which may be related to running the car for quite long while the alternator not working. While driving when the car's battery voltage was dropping with alternator died, I could definitely feel the car's engine were not running as normal during that time, kind of like engine being muffled and not producing enough power. However, it was in Yellowstone and was 7pm, so I felt it was better for me to drive as close to entrance (where my camping site was) as possible.

Anyone have a suggestion what could be wrong? The battery is new and I just replaced all 6 spark plugs.

Thank you very much!

Just because you replaced the alternator does not mean the alternator is good
I would bring the alternator back and get it warrantied (somehow).
Get a good one put in.
Then clear all the codes and see which ones come back.
Then deal with the ones that come back.

It turned out that one of the plug wasn't connected properly. I had to remove that plug and re-connect it. But just looking it by eyes you wouldn't think that the plug was not connected properly, however, after disconnect it and reconnect it, all symptoms are gone.

Thanks!