emmanuelNigeria

I am sorry if these questions have been answered before. Though i searched for these problems but couldnt get a satisfactory answers, so i decided to bring it up review, in case we have new ideas. my acura mdx is on 109k miles. About 3 weeks ago i noticed my vtm-4 light was showing and also discovered that my 4 wheel drive was not engaging, after two days the check light came on.
last week i decided to go for engine scan and these are the problems listed with codes:
1. 23-01 knock sensor (PO No signal 325)
2. 13-01 left front wheel speed sensor open or short
3. 61-01 battery voltage failure (but at first attempt my
car usually starts)
Please, i will be glad to have some ideas how to go about it and where those sensors are located. is there anything to do or check before replacing anything at all? Please i need answers as soon as possible.
Thank you.

emmanuelNigeria

please still waiting for any ideas. in order not to cause further damage to the system, i ve packed the car and start using my honda.... though plan to take it for repair, only that i want to have an idea of what to expect. have not been faced with this problem before