Volkswagen Repair: Reading codes, coolant temp, engine coolant

Question
Thanks for your help Paul. I spent some time today looking for loose wires. Unfortunatley I didn't find any loose. I will keep looking. Is there an easier way to find shorts in an electrical system? Is there some sort of testing tool?

Again, thank you for the response. I think you are right about this since these codes came on one day all at the same time.

Matt


-------------------------
Followup To
Question -
Paul,

I know your profile did not mention Passats however I was hoping you could explain how to know what part to repair based on a code. I recently got 3 codes from my 99 V6 Passat. They are "16521 P0137 O2 Sensor Circ.,Bank1-Sensor2 Low Voltage", "16711 P0327 Knock Sensor 1 Circ Low Input" and "16501 P0117 Engine Coolant Temp.Circ Low Input".

What I would like to know is:
a) P0137 - does this mean the sensor needs replaced and if so how do I know which side of the car it is on? There are 4 o2 sensors, 2 in each exhaust. I would replace all 4 but they are $90 a piece. I hope to only do 1. Someone told me to try the spark plugs and wires first. It has 50,000miles with all original plugs and wires.

b)P0327 - basically the same question for the knock sensor. Does low input mean it's bad?

c) P0117 - not worried about this one, I think it will be the easiest to replace. But again does a code always mean to replace the part?

d)Could P0327 and P0137 be related to other part or parts being bad? In other words is it possible that they aren't bad?

I REALLY appreciate your help as I am trying to fix this myself. Mainly because it has a rear main seal leak that I can't do myself and it will be costly.

Thank you,

Matt Eustice
Answer -
OK, I think all of your codes are related to the same common problem.  Check the brown ground wires attached to the head at the transmission side.  VW's are known for broken ground wires.  This would explain the low voltage readings. Pull each ground wire to make sure their tight.

Paul

Answer
Matt,

I would just visit a dealer in your area, and ask a service adviser if they could take a quick look or have a mechanic take a look.  This repair is not worth writing out a workorder for, and it's good PR for them.

If it is a ground, they'll show you, and you can repair it.  I would add a 4" lead to the broken wire, so it's not as tight.

Paul