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cardoctor71, ASE Certified Technician
Category: Toyota
Satisfied Customers: 675
Experience:  ASE MasterCertified Tehnician with 35 years experience diagnosing and repairing all makes and models of cars and trucks.
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Engine has had a moderately loud tick for about 6 months.

Customer Question

Engine has had a moderately loud tick for about 6 months. Tick frequency increases as the engine RPM increases. A back yard mechanic and a dealer have both said that the tick is not comming from the valves. The dealer said that they would have to take the engine apart to discover where the tick is coming from, which given the price of the diagnostic test, may not be worth it, given the age of the car (2001 Toyota Highlander, 207,000 miles). Last night, the check engine light came on as well as the VSC light. O'Reilly auto put their little computer on the car and said it was the knock sensor that may be bad. How should I proceed?
JA: Does the light stay on, or does it blink?
Customer: The light stays on.
JA: Are you hoping to fix this yourself? What have you tried so far?
Customer: I tried disconnecting the battery to reset the computer, but the light has come back on. I am not sure it is the knock sensor. Could the knock sensor be causing the engine tick? How should I proceed?
JA: Anything else you think the mechanic should know?
Customer: Yes. An engine oil analysis done two weeks ago read this:
All wear levels appear within acceptable limits for first sample. Silicon level (dirt/sealant material) satisfactory. Water content acceptable. Viscosity within specified operating range.
Submitted: 1 year ago.
Category: Toyota
Expert:  cardoctor71 replied 1 year ago.

The knock sensor is most probably NOT failed but rather doing its job properly ,The tick noise has gotten worse to where the noise is now traveling through the engine block and severe enough to trigger the knock sensor into action, next it will retard the timing and make the vehicle very sluggish, most likely cause is a collapsed lifter at the least and a wrist pin on a piston worse case scenario, unfortunately the engine will have to undergo some degree of tear down to pin point the issue, I would start with removing the valve covers and thoroughly inspecting the cams and rockers for unusual wear Please accept my answer, if you have any further questions I will answer them until you are completely satisfied with my answers.

Expert:  cardoctor71 replied 1 year ago.
Expert:  cardoctor71 replied 1 year ago.