Two days ago while on the highway after a hard acceleration (I think) the battery light came on but the car seemed to be working just fine. After I stooped at my destination and started it again the light was gone. I was told to check the battery cables since the battery is fairly new.
Today, as I was driving the car hesitated some and the check engine light came on. I went back home and checked the codes and got P0333 - Knock sensor 2 Circuit High Input (Bank 2).
I erased the codes and cleaned the battery terminals; the positive was very clean bu the negative had a little build up of the white stuff but overall did not look too bad. I took the car for a ride around the block and seemed to be working OK.
What are the chances it was just a bad connection or will the message come back and I will have to replace the knock sensor?
I have seen a couple of write ups and videos on replacing the knock sensor and while it does not look terribly complicated I might prefer having it done by a mechanic at this time. Looks like parts are around $120-$150 for the knock sensor and manifold gaskets (aftermarket parts) any idea what the labor cost would be, obviously not at the dealer?
I might need to take a 150 mile trip before the car is repaired, if the code comes back, does it hurt to drive the care with it or it will simply go to the limp mode and not go over 3,000 rpm but otherwise drive safely?
Any help or information would be greatly appreciated.

 

VTGBoss, having clean terminals is good, but the cables tend to fail inside the wiring just beyond where the cables connect to the terminals. What I recommend you try first is to let the car sit say overnight (want the engine at ambient temperature). You will then start up the car, turn on the A/C on high (and lowest temp), the seat heaters and rear defroster. We are putting a good load on the alternator. Let the car come up to temp (about 5 minutes). Now, turn off of the electricals and the engine. Open the hood/bonnet and then remove the cover off of the battery and cup your hands over (DO NOT TOUCH!!!!!!!!) the battery terminals. Are they about the same temp as other parts under the hood or do you think you could fry and egg on a terminal or two? If you think you can fry an egg, then that battery cable is bad. Lets see what you have with the battery first as this can cause random error codes.

 

I followed your instruction and run it for 6 or 7 minutes until the engine temperature gauge was right around normal. I checked the battery terminals and the negative was cold bu the positive was fairly hot; I am not sure I could fry an egg on it but i could not hold my finger on it for any length of time. Is this an indication of a bad positive cable? how easy/complicated is to replace it and what is the part cost? Can this be the cause first, the battery light which never came back and second the P0333 Code? Thanks in advance.

 

VTGBoss, if one is fairly cool and the other is dramatically different, then yes, this is a bad cable. You can pull the cable and take it to your local auto parts place. They will be able to match up the cable. There is nothing special about the cable.

As for why it causes the P0333 code, it has to do with how the ECU looks at the parameters. In short, the ECU assumes that the battery voltage is steady and at 13.7 VDC. If the voltage starts to deviate from that (the cable getting hots tells me that it was dropping some of the voltage due to internal wiring losses being turned into heat), then the computer does not have an accurate thing to compare the engine parameters against. This can lead to random error codes coming in.

 

Thanks Thermo. Where does the positive battery cable connect? I see the OEM cable (~$90) that looks different than the "exact" replacement cables at the auto parts stores ($10-$30). The original cable seems to go from the battery to somewhere and from there fork to somewhere else or maybe it is just a cable support? The after market cables seem to be fairly straight, some with small piggy tail attached to the terminal. the two pictures below are the OEM part.



The manual shows what appears to be a straight cable from the battery to the starter solenoid...



There are a number of cables that supposedly fit my car but none looks even close to the original.
Here are the ones at Auto Zone which seems very generic and vary in length from 15 to 72 inches and seem to fit any car:
https://www.autozone.com/batteries-s...eVehicle=false
This one at O'Reilly's looks somewhat close with two wires going directly from the battery to 2 places:
https://www.oreillyauto.com/detail/b...ve+cable&pos=8
Is there a write up somewhere that show the routing of the cable and the best way to access the connections?
I drove the car for a few miles since I cleaned the terminals and reset the codes and the codes have not come back...yet (keeping fingers crossed). Is it safe to drive the car under these conditions? If the knock sensor is indeed bad and the code comes back, is it safe to drive the car? I assume the performance would be less than optimal but the car would not die and leave me stranded, right?
Again, thanks for the help, much appreciated.

 

VTG, the cable runs from the battery to the starter and then on over to the alternator. If you can get the OEM cable for $90, then for peace of mind, that may be the way to go. Replacing it is not hard, just takes a little bit of time as they run the cable in a not so easy spot between the starter and alternator. The other tidbit, make sure to disconnect from the battery first and make the battery connection the last one you make.

 

Looks like the OEM cable or the one at O;Reillys would be the better options. The OEM forks/splits at the starter and the one at O'Reillys has two cables coming out of the battery connector, one going to the starter and the other to the alternator, one would think. Does it make a difference?
I read that some have clipped the cable at the starter, left the portion going to the alternator in place and used a new cable between the battery and starter. Apparently it is difficult top get to the alternator connector and might need to remove the compressor, although this is not verified.
https://www.jaguarforum.com/showthre...Positive+cable
Is there a diagram showing the position of the connectors, starter and alternator so I don't have to crawls all over...or under? I would think there is a write up or YouTube video somewhere with the procedure.

 

Here is a link to a video for the installation of the battery cables. Not the most efficient mechanic but it show where everything goes.

 

VTG, I have heard of others cutting the cable at the starter and only replacing the small section. IT is up to you. Electrically it is all the same whether you go with the 2 cable or 1 cable setup. The big thing is making sure the connections are tight and the lugs on the end of the cable(s) are clean and not rusted.

 

Thanks again Thermo. The codes have not come back so far. I will get the OEM cable and replace the existing, I have a couple of long extensions that hopefully will allow me to reach the alternator nut from under the battery tray and going between the radiator and engine block.
I am thankful for this forum and the help it provides.