Rx300 Gas Knock

[bowtie3]

My wife's 2000 RX300 FWD [ 55,000 miles ] has a periodic gas knock. We've always used 87 octane in it. When the gas knock shows up I pull the ECM fuse for a minute or so and that solves the problem until the next time. I guess the question I have concerns the 2 knock-sensors located on the intake manifold. Does the RX300 have a history of this problem? I have a tech manual for the same year of Camry [ same engine, trans, etc. ] and it says to check the 2 knock-sensors with an ohm-meter. The sensors aren't that difficult to replace once the intake manifold is removed. [ Toyota tech said it's about a 1-hour job ] Park Place Lexus in Plano, Texas has the sensors for about $130.00 each incl. shipping. [ I order from them often ] The dealer says that knock-sensors aren't covered under the Certified Warranty [ NO surprise ] and the total cost to the customer is about $400.00 to replace 1 sensor. Has anyone else had to replace the knock-sensors on their RX300? Thanks.

[monarch]

Knock sensors should last the life of the car. The wiring to the sensors can sometimes get accidentally disturbed / disconnected during the course of engine maintenance /service work, however.

Try a tank on premium gas. If the pinging goes away it might mean the fuel mixture is running leaner than it used to or that the engine temperature is slightly higher than it used to be.

[SKperformance]

87 octane is among the begining of your carbon build up troubles leading to knocking. If it is knocking it is pretty sever in a modern engine as they can usually !Removed!/advance the timing to elimnate it completly.

get a Motorvac

and

use premium gas from now on.

[RX in NC]

If you'll occasionally add a bottle of relatively generic fuel injector cleaner to your gas tank, you may find that this is the simplest and least expensive way to avoid knocking or pinging. My wife's 2000 RX300 gets a bottle of this stuff at every oil and filter change I perform, and knocking or pinging has never occurred. We also run 87 octane, have never needed anything higher, and the vehicle reached 100,000 miles earlier this week. Before spending any money on new sensors or expensive clean-out procedures, try some fuel injector cleaner first. I would add a bottle to two or three successive tankfulls and then see where you stand. Let us know if this helps.

[Lexusfreak]

87 octane is among the begining of your carbon build up troubles leading to knocking. If it is knocking it is pretty sever in a modern engine as they can usually !Removed!/advance the timing to elimnate it completly.

get a Motorvac

and

use premium gas from now on.

Agreed. B)

[timonly300]

I was having major problems with pinging on my 2001 rx300 right after I bought it (51,000 miles). Did numerous decarbs (by the dealer), checked everything possible, always ran premium gas, fought with lexus customer satisfaction and lost. Bit the bullet and had them replace the knock sensors (both of them). $900 - $1,000, but it actually worked. It's a shame they wouldn't cover it, but I'm glad it's fixed.

[Ericok]

What's the point of paying extra for a "certified used" car if stuff like the knock sensor is not covered?

[bowtie3]

I was having major problems with pinging on my 2001 rx300 right after I bought it (51,000 miles). Did numerous decarbs (by the dealer), checked everything possible, always ran premium gas, fought with lexus customer satisfaction and lost. Bit the bullet and had them replace the knock sensors (both of them). $900 - $1,000, but it actually worked. It's a shame they wouldn't cover it, but I'm glad it's fixed.

My wife's 2000 RX300 FWD needed a rear engine mount a few months ago. The service rep at the ONLY Lexus dealer here said that an engine mount is " a wear-item " and wasn't covered under the Certified Warranty. Rather than pay the dealer the $400.00 for replacing the rear engine mount I ordered one from Park Place Lexus [ about $47.00 incl. shipping ] and replaced it myself in about 2 hours. It's good for a vehicle owner to get under their cars once in a while. I've owned many vehicles in my life and never had to replace an engine mount because it broke! When her car had the " front strut-mount clunk " it took three times for the dealer to fix the problem. On the last trip they told me that the " fix " performed at that time WAS NOT covered under the Certified Warranty and charged me an hour's labor [ $90.00 ]. A few months ago the car began idling too high and would really jerk when put into gear . After two trips to the dealer for this problem [ No Problem Found ] the check-engine light finally came on. It seems as though if the technician can't get a computer to diagnose a problem, then there IS NO PROBLEM. Turns out that the throttle position sensor was bad. Why didn't they suspect the throttle position sensor in the beginning? I hope the warranty on their dopey technicians is better than the one they have on their Certified Used Cars. Her cars' " meaningless " Certified Warranty expires in April '06. The chances of them ever seeing me again are pretty slim!

[JSmith]

My wife's 2000 RX300 FWD [ 55,000 miles ] has a periodic gas knock. We've always used 87 octane in it. When the gas knock shows up I pull the ECM fuse for a minute or so and that solves the problem until the next time. I guess the question I have concerns the 2 knock-sensors located on the intake manifold. Does the RX300 have a history of this problem? I have a tech manual for the same year of Camry [ same engine, trans, etc. ] and it says to check the 2 knock-sensors with an ohm-meter. The sensors aren't that difficult to replace once the intake manifold is removed. [ Toyota tech said it's about a 1-hour job ] Park Place Lexus in Plano, Texas has the sensors for about $130.00 each incl. shipping. [ I order from them often ] The dealer says that knock-sensors aren't covered under the Certified Warranty [ NO surprise ] and the total cost to the customer is about $400.00 to replace 1 sensor. Has anyone else had to replace the knock-sensors on their RX300? Thanks.

This summer I bought a '01RX300 with 26k miles. The engine would always ping when accelerating up a small hill on my way home. Dealer response was simply to use premium fuel. After 4 wks, and noticing unusual oil consumption, discoverd the engine was sludged. Fortunately, dealer behind it was straight up and all ended well. Be religious with oil changes.

[kalo93406]

I had pinging going up hills and an engine check light. They changed the MAF sensor and the pinging went away, but then i got another engine light.. this time they say Knock Sensor Open code. They seemed to want to check the wiring more than replace the knock sensors. They also said knock sensors are NOT likely to fail. I didn't have time to have them check the wiring, so still have the problem. Will be trying to do it this weekend. One other tidbit is there were some paw prints under the hood, so some varmit was under there and i suppose it is possible that it chewed through some wiring.

Can anyone help me with tracing the wiring for the knock sensors?

Thanks! Roger