So over the past two ways the CEL and VSC off lights have illuminated in my '99 LS400. Sometimes the car would run and idle rough, almost dying, and other times it was fine. I pulled the codes once and got P1349, which is a code related to the OCV and some misfire codes (P0300, P0301, P0305). I searched the forum and came across multiple threads, these two being the most helpful:

https://www.clublexus.com/forums/ls4...ode-p1349.html

and post #36 from this thread:

https://www.clublexus.com/forums/per...ml#post6150886

I first cleaned the OCV as instructed, reset the ECU by undoing the battery, and reinstalled the OCV. A few miles down the road and the lights come back on. Next, I try the test as mentioned in the second link I posted, the OCV checks out good. So I pulled the codes for a second time. This time I only got the P1349 and a new one, P1656, which is also related to the OCV. Should I just go ahead and replace the OCV and hope that fixes it or should I try something else? My only thought is that the OCV is beginning to go bad, thus only sometimes causing the car to run rough. Any help would be appreciated.

 

Did you check your oil? I cleaned mine up and the light still came back on until I topped off the oil.

 

It's full, I checked it. I changed my oil last week, would that have anything to do with it?

 

If miss fire is on all cylinders on same side then it is related to OCV, If not then try cleaning throttle body and air mix path

Any way start with simple, free fix first..check below post
https://www.clublexus.com/forums/ls4...ml#post8907041

Dont forget to reset KAM by pulling battery cable after finishing the clean,

 

So go ahead and buy a new OCV?

 

try cleaning throttle body and air mix path

 

I would check the OCV at a bench applying only 8.5V using a DC power supply unit. It should work well with that much of voltage. I also would check the strainer. Problem is it's not easy to access. May be I would use a compressor to clean it quickly and simply.

 

I think you must have a dirty/clogged screen here is a photo I copied...

 

I ordered the part from Toyota, it will be here in the morning. I'm going to try that before I disassemble all of that. Is there a DIY to tear the engine down to that point? Also, would running some Marvel Mystery Oil or AutoRx through the engine possibly clean some of that up?

 

In my case that was the issue. It happened when the temps got down to the single digits. I cleaned it up and the code came back but not right away. I checked the oil and it was low so i added oil and it has not come back since. i also took it on a 6 hour road trip to really push oil through the OCV.

 

I'll double check the oil after the new OCV is installed and go beat on the car some, I'll report back with the results.

 

I had Bank 1 misfire and pulled the same code as you. Surprisingly I used seafoam in the oil and ran it for a day and it cleared up the misfire and codes. I immediately changed the oil. Worth a try if OCV cleaning is not working.

 

I've driven about 30 miles since I replaced the OCV, so far so good, no codes. I plan on running a cleaner through the crankcase just to be sure the internals are clean. Problem is I just changed the oil last week and I know with seafoam you aren't supposed to drive with it in the oil that long.

 

I would just hold off on the seafoam in that case.

 

Has it fixed the rough idle? Did you replace both ocv's? Or just one bank