2013 ES 350 with 29,000 miles to date . Purchased new in 12/28/2012. Spark plug failure at 7800 miles ,then again at 15000 miles and now again at 29000 miles. Of course car is no longer in warranty. I recently serviced this car myself and replaced all 6 spark plugs and the flashing "Check Engine Lite' was reduced to a steady indication, and the engine runs good. Dealership want s to replace again the fuel injector, and maybe the wiring harness. My inspection of the wiring harness found no issues. Something is destroying the spark plugs in cyclinder #1 .I am suspicious of a bad ECU unit. I need some help. Very disappointed with this very expensive ES 350. Frank in Connecticut

 

A few more details would be helpful. What part of the spark plug is failing, electrode damage, glass insulator, carbon tracking? Is it the same cylinder each time? What trouble codes are being stored with the check engine light? Was the fuel injector on the misfiring cylinder replaced before? A vacuum leak on the fuel injector o-ring could cause a lean fuel mixture for that cylinder.
The proper way to find the problem is with a high tech (and costly) diagnostic tool in the hands of a skilled technician. Since you are out of the factory warranty you may want to seek out an independent repair shop that is familiar with Toyota and Lexus vehicles.

 

The original diagnostic was P0301. The first 2 sparks plugs were replaced under warranty by a local dealership. I did not see those 2 units. Invoices for these replacements indicated P0301 errors. The first invoice at 7800 miles stated "Verified Concern, Code P0301 Cylinder #1". "Removed the intake manifold and swapped spark plug 1 with 6, coil 1 with 4 and injector 1 with 2." "Installed the intake manifold and started the vehicle." "The misfire now traveled to cylinder 6." "Removed and replaced the cylinder 6 spark plug and the misfire is now gone".

The same problem occurred at approximately 15,000 miles and another spark plug replacement was made. I don't have a copy of that dealer invoice. Now at 29,000 miles, out of warranty, I returned to the dealership for repairs. Diagnostic testing pointed to Cylinder #1 issues again. This time, I refused the dealership's repairs. I changed spark plugs 2, 4, and 6. The same misfiring occurred. The I changed sparks plugs 1, 3, and 5 and the misfiring was gone. I examined the plugs and could not find an issues with any of the removed plugs. Something has destroyed 3 sparks plugs in cylinder #1 as evidenced by the 3 occurrences. Although the check engine light is off, the engine is still not running as smoothly as before and there is pronounced hesitation from time to time.

Also, the dealership has been performing all of the DTC codes using their computer scanner. I have been unable to get my Actron Auto Scanner, CP9680, to read the codes. There are no fuses related to the DTC connector. Is it possible that the dealership is blocking the use of the Actron Auto Scanner at the DTC connector?

 

I had a P0301 on my 2000 RX. It was the ignition coil. Once that happened, I replaced all the coils, got them from Autozone, lifetime warranty too. I think this is your problem.

 

Obviously swapping parts has not fixed the problem so it must be something else related to cylinder 1. Some other things that come to mind are electrical wiring issues to the coil or injector and vacuum leaks on the injector or intake manifold. In order to find these type of problems a high tech diagnostic tool is required to look at current ramps, fuel trims and other data. A skilled technician should be able to compare the cylinders and identify the problem.

Regarding you Actron scanner, I doubt Lexus is blocking its use on your car. Have you tried it on any other cars to see if it works on them? You might stop by a parts store and see if their scanners can read codes for you.

 

First of all, I want to thank you for your assistance in trouble shooting this issue. I believe you are correct in advising profession help. I may have to go back to the dealership. This problem should have been addressed with the first two failures when vehicle was in warranty.--live and learn. My Actron works well on my 2004 Chevy Van. With the Lexus, there is no communication. I tried using the Actron with and without Actron internal batteries. I am able to power up the dashboard lights by pressing the start button without applying brake pressure. Is there a secret trick that I am missing?

I also checked the DTC connector with a Fluke Multimeter. I know from the Chevy that pin 16 of that connector is common at minus 12 volts DC and pins 2, 3, 5, & 6 are positive. There are no problems with the Chevy Van. There are no voltages at the Lexus DTC connector. Are electrical drawings of the ECU (engine control unit) available?

 

Pin 16 on the DTC connector should be +12 volts at all times and pins 4 & 5 are grounds. Are you sure you are reading the pin numbers correctly? Its on the upper left corner of the ES350 lexus connector. If pin 16 really has no power then there may be a blown fuse.

 

In regards to the failure of the Actron Analyzer ,I found a very small fuse box located near the DTC connector. So small ,could not read the writing on it. --Sure enough that DTC fuse was there. Replaced it and all is well. You are also correct that the voltage at pin 16 of the DTC connector is Plus 12VDC measured to body frame. Thanks Again for your help .Frank