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lexpert, Lexus Master tech
Category: Lexus
Satisfied Customers: 9974
Experience:  Master Certified with lexus, 8 years experience with Lexus
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1998 Lexus GS300: valve timing..wiring..timing belt..the cam sensor

Customer Question

I have a 1998 Lexus GS300 and I have a code for valve timing and would like to replace the cam sensor. I cannot see any wiring going onto the timing belt area and I have yet to remove the cover. Do you have a picture of the location of the cam sensor as well as ideas for valve timing issues. thanks
Submitted: 7 years ago.
Category: Lexus
Expert:  lexpert replied 7 years ago.

Hello and thank you for using just answer!

Whar is the code # XXXXX in the computer here and did this pop up after a repair was performed?

Customer: replied 7 years ago.
The problem just happened with no previous repairs. The codes that I have now are PO300 thru PO306 (misfire), PO110 (air intake temp), PO1346 (WT sensor, CPS ) , PO1349 ( variable valve timing). The car will run fine then at times miss and shutter. Then run fine. I thought that the camshaft position sensor would be the most likely problem. I need to get the car smogged so I need to resolve this situation. thanks
Expert:  lexpert replied 7 years ago.

This will not be a cam position sensor.

The p0300-p0306 are happening because if the 1346 and 1349 codes......

If you clear the codes and then drive the car with the scan tool what code or codes pop up first here?

Customer: replied 7 years ago.
1346 and 1349. The car can go for a few days before the problem occurs
Expert:  lexpert replied 7 years ago.
P1346 is a code specific to the v8 version GS which is a said this is a gs 300 right?
Customer: replied 7 years ago.
correct and I do have a code p1346 as well as p1349. I do realize that the codes Po300 thru Po306 are just symptoms of the real problem
Expert:  lexpert replied 7 years ago.
answer my question above, is this a gs300 with the 2jz-ge engine or a gs400 with the 1uz-fe engine????? The 1346 code shows to only be a valid GS400 code.....
Customer: replied 7 years ago.
sorry. I had to go outside to get the engine #. It is a GS300 with engine # XXXXX
Expert:  lexpert replied 7 years ago.

this must be aglitch in your scan tool then, ignore the 1346 code then.

Have you made any inspections on the timing belt yet?

Have you looked INSIDE the engine at all?

Customer: replied 7 years ago.
no, not yet.
Expert:  lexpert replied 7 years ago.

P1349 is for the variable valve timing. Basically the computer commands the camshaft to move position and it does this by means of oil pressure through the oil control valve on the front of the engine, you will see a metal line that holds the high pressure oil near the front.

This code is most commonly caused by one of 3 things here:

1- Stretched or jumped timing belt. Do be aware this is an interference motor, if the belt breaks it's game over for this engine.

2- Deposits inside the engine such as gel/sludge that restrict the oil passages and the oil control valve. Removing a valve cover to inspect the condition of the intenal engine is a good idea here.

3- Bad oil control valve or a bad vvt-i camgear actuator.

lexpert and other Lexus Specialists are ready to help you
Customer: replied 7 years ago.
I have yet to inspect the t-belt but I do not believe that this is the problem because the car will run great then all of a sudden like $#@*! I can pull the valve cover and inspect for sludge but the valves were done about 50 K ago so I don't know if they would get that clogged up in that time. Can you explain the oil control valve , that sounds like a more likely suspect. As for the cam gear actuator wouldn't the problem be there all the time instead of on and off? thanks
Expert:  lexpert replied 7 years ago.
Cam gear actuators and oil control valves can cause intermittent issues. If you pull the 4 5mm hex bolts that hold the front black cover over the timing belt and valve cover area you expose the top of the timing belt and these 2 items, the cam gear actuator is built into the funny looking cam gear pulley that the timing belt rides on the driver side. The oil control vavle is right behind it on the valve cover, you will see the metal oil line and the 2 wire electrical connector to it.
Customer: replied 7 years ago.

how do you find out which is the problem? can the oil control valve be diagnosed or do you just need to replace it? How would you recommend me to continue with this situation?

Expert:  lexpert replied 7 years ago.

The really good scan tools like the $5,000 one I have from Lexus has the ability to perform an active test on the oil control valve.

Being that this issue is intermittent you may not be able to duplicate this with an active test.

I would double check the engine for deposits, do a synthetic oil change here and at least remove the oil control valve and see if it looks dirty to consider replacing it or not.

I have had a few of these with bad cam gear actuators also but that is not nearly as common as the oil control valves.

Customer: replied 7 years ago.
thanks Peter you have been a great help. You have gave me some direction.