So my 99 lexus rx 300 with 200K+ is throwing the codes for both knock sensors. This most likely means that the wiring harness is bad. It’s a lot of work to get to the harness (and sensors) so I’m considering putting in two new sensors (and the coolant bypass hose ofcourse) while I’m changing the har…

I can’t tell if you are going to do the work or if you are asking if you should buy the parts and pay someone to install them. If you furnish parts the mechanic will not warrantee them and if they are bad you will pay labor to remove and replace. Yes, new parts can be bad but not common.

Some examples, I bought a Standard T-Series TPS sensor, failed just after 1 year, original lasted 20+ years. Airtex Advantech EGR valve, failed within 1 year, original lasted 20+ years. Thermostat housing from Advance Auto, don’t remember brand, leaked after 4 months, original lasted 12 years. Th…

Thanks for the notes guys. I’ll be doing the install myself. I’m staying away from the budget line of parts. The OEM part is close to $200 a pop from the dealer. The OEM-like Standard Motors (not T line) or Airtex part is about $100, which may just be a reboxed Denso. I believe it’s Denso that make…

I’m not too good at diagnosing to be honest. There’s a couple guys on youtube who have great vids on diagnostics with the scan tools, schrodinger’s box and scanner danner. Most “pro” mechanics aren’t good at diagnostics either, from my experience. They often just throw parts at it which I can do mys…

[image] Funkyfresh: This most likely means that the wiring harness is bad On what do you base this assumption? Is it not more likely that transient pulses are coming from the piezoelectric crystals (the knock sensors) due to pinging or some other cause of mechanical inputs to the sensors? W…

The engine is fully service up 200k+ Both Knock sensors went bad simultaneously and the tech who originally looked at it claimed he was able to get a mirror or scope under the intake and observed some signs of rodent damage on the harness. I was skeptical because I’ve fixed symptomatic CEL codes by…

[image] Funkyfresh: Both Knock sensors went bad simultaneously The odds against that happening are very very high. If critters might be nibbling on the harness I’d suspect that first. Not sure I’d spend $200 on 2 sensors based on that.

It’s a good bet there’s an electrical problem common to the knock sensors, but there’s other possibilities that would explain knock sensor codes. A tank of bad gas, spark plugs who’s electrodes have too wide of a gap, problem w/the advance/retard mechanism, variable valve timing problem, etc. It…

[image] Funkyfresh: If the engine was pinging the knock sensor would do it’s job and retard the timing. Only to a point. If the sensor detects a chronic misfire it’ll trip a fault code. However the rodent damage in this case just may be the culprit.

Knock Sensor to replace or not

Maintenance/Repairs

ChrisTruck September 6, 2017, 4:13pm 3

I’ve had a few new parts in the last 2 years that flaked out within a year or didn’t work out of the box. I’d stay away from the budget lines they have. If it’s a lot of labor to install, try to get OEM.

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Knock Sensor to replace or not

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