Toyota Repair: 1999 Toyota Sienna, actron scanner, toyota sienna

Question
QUESTION: Hi Ted,

I'm sorry for the duplicate message if you did receive the first question, however, I did not receive a receipt email after the submission which makes me think it did not get submitted.

Anyway, I have a 1999 Toyota Sienna LE with 246,000 miles and it keeps giving check engine codes for the knock sensors.  Sometimes only one sensor (either one) or sometimes both.  The code will come back within 10 miles, usually less, after clearing it.  I have been listening to the engine, both on the top end and bottom and at various rpms and cannot hear anything unusual except the valvetrain tick that it has had forever.  I understand it is difficult for you to diagnose something like this without the vehicle, but I'm just looking for you to maybe give me some ideas to try out, maybe someway of testing the sensors without actually getting to them? Anything would help and be appreciated.  Also, if you think it could help, perhaps the tick has something to do with this, I could record it and post a link to youtube.

Thanks!

ANSWER: A valve train ticking noise will not turn the check engine light on, can you let me know exactly what trouble code numbers are in the computer now and I will help from there.

---------- FOLLOW-UP ----------

QUESTION: Ok, here are the codes from my Actron scanner:

P0325
Knock Sensor 1
Circuit (Bank 1)

P0330
Knock Sensor 2
Circuit (Bank 2)

But like I said sometimes only 1 will come on, sometimes both, which I find strange.
Thanks again!

Answer
Thanks for that info, the least likely cause is the knock sensors, there are two other causes, one is a wring problem( open or shor tcircuit) between the sensors and the ECM or the ECM itself, which I doubt very much. So that leaves the wiring, this is where you need to inspect the wire harness closely. Remove the plastic engine cover and inspect the wires and the insulation, the knock sensor sub harness comes from under the intake manifold and connects to the engine main harness, many times we have found the rodents chewed on the wire insulation and caused shorts and open circuits like this. Look for any signs that rodents may have gotten in the engine compartment such as droppings or urine, they also like to chew up the air filter so check for that, if you see any evidence that there may be rodent infestation you most likely have some wires chewed up.