Check engine light: vacuum leak
CL Community Team
Joined: Apr 2001
Posts: 16,533
Likes: 1,379
From: Austin, TX
Salim
Driver
Joined: May 2006
Posts: 72
Likes: 1
From: tx
OK, I'm stumped again 
I reconnected the hose behind the airbox, and used my scanner to clear the check engine lights.
However, the VSC and TRAC OFF indicators are still on. When I plug in a scanner, it doesn't find any error codes active.
Does it take some normal driving to reset?
I reconnected the hose behind the airbox, and used my scanner to clear the check engine lights.
However, the VSC and TRAC OFF indicators are still on. When I plug in a scanner, it doesn't find any error codes active.
Does it take some normal driving to reset?
CL Community Team
Joined: Apr 2001
Posts: 16,533
Likes: 1,379
From: Austin, TX
OK, I'm stumped again
I reconnected the hose behind the airbox, and used my scanner to clear the check engine lights.
However, the VSC and TRAC OFF indicators are still on. When I plug in a scanner, it doesn't find any error codes active.
Does it take some normal driving to reset?
I reconnected the hose behind the airbox, and used my scanner to clear the check engine lights.
However, the VSC and TRAC OFF indicators are still on. When I plug in a scanner, it doesn't find any error codes active.
Does it take some normal driving to reset?
Your RX is telling you there is a problem detected in your braking system.
Salim
Driver
Joined: May 2006
Posts: 72
Likes: 1
From: tx
Uh, oh, that is never news soeone wants to hear.....
How do I diagnose it further?
Here is the complete history:
1. TRAC OFF, VSC and CEL appear
2. Codes show P0442 & P0446 (EVAP)
3. Discover vacuum hose behind airbox was disconnected
4. Re-attach hose, and use scanner to clear codes
5. CEL is off, but VSC and TRAC OFF remain lit
How do I diagnose it further?
Here is the complete history:
1. TRAC OFF, VSC and CEL appear
2. Codes show P0442 & P0446 (EVAP)
3. Discover vacuum hose behind airbox was disconnected
4. Re-attach hose, and use scanner to clear codes
5. CEL is off, but VSC and TRAC OFF remain lit
CL Community Team
Joined: Apr 2001
Posts: 16,533
Likes: 1,379
From: Austin, TX
As suggested, try removing battery power, to see if the brake (part of the ecu) clears out.
Lexus has a port to check the brake error code. I am not sure if that port is OBDII compatible.
Salim
Lexus has a port to check the brake error code. I am not sure if that port is OBDII compatible.
Salim
Driver
Joined: May 2006
Posts: 72
Likes: 1
From: tx
OK, after several weeks, I'm still stumped.
After I discovered that my vaccuum hose was disconnected, I reattached and cleared the CEL. The CEL never came back, and scanner doens't show any codes.
However, the VSC and TRAC OFF remain constantly on.
1. Pulling the EFI fuse didn't clear those lights.
2. Unplugging the battery did not clear the lights.
Any other ideas? The fellow at Autozone seemed fairly knowledgble, and claims that those sensors can only be reset by the dealership. Salim mentioned a brake code, but I could find any further details.
(On a positive note, gas mileage seems improved since I reattached my vacuum hose)
After I discovered that my vaccuum hose was disconnected, I reattached and cleared the CEL. The CEL never came back, and scanner doens't show any codes.
However, the VSC and TRAC OFF remain constantly on.
1. Pulling the EFI fuse didn't clear those lights.
2. Unplugging the battery did not clear the lights.
Any other ideas? The fellow at Autozone seemed fairly knowledgble, and claims that those sensors can only be reset by the dealership. Salim mentioned a brake code, but I could find any further details.
(On a positive note, gas mileage seems improved since I reattached my vacuum hose)
Driver
Joined: May 2006
Posts: 72
Likes: 1
From: tx
I'm still struggling with the same problem: no CEL, bit VSC and TRAC OFF appear.
I happened to be near the dealership, so popped in to show them the problem. The service manager attached his scanner, and couldn't find any codes reported. He suggested that the VSC TRAC OFF combination may be caused by a sensor checking tire sizes and that I should fill up the tires with air. Beyond that, still no clue how I can get this resolved.
The mystery continues for me...
I happened to be near the dealership, so popped in to show them the problem. The service manager attached his scanner, and couldn't find any codes reported. He suggested that the VSC TRAC OFF combination may be caused by a sensor checking tire sizes and that I should fill up the tires with air. Beyond that, still no clue how I can get this resolved.
The mystery continues for me...
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Rookie
Joined: Feb 2013
Posts: 66
Likes: 0
From: NY
Just a note, my air box is not tightly sealed, only used zip ties. The oil change dude lost two clips for the air box, so I had to improvise. Can't just buy the clips, have to buy the entire air box assembly for several hundred dollars. CEL and VSC light would come on occasionally with air box intact, seems to come on less now with zipped tied, leaky air box. So air filter and air box is not a fix. I have had best results with just re tightening the gas cap. Car runs no different with lighs on or off.
When I was re-installing the air box this past weekend, I noticed that the three mounting bolts with the rubber grommets could not be tighten enough to seal properly and the box had some "wiggle" to it. Would this be an issue for a vacuum leak?
Also, when ever I fill up gas, when removing gas cap I don't feel suction or hear any "pop" sound indicating absence of vacuum. Gas cap was recently replaced. Would this also be an issue for a vacuum leak?
Pole Position
Joined: Sep 2012
Posts: 338
Likes: 16
From: Oregon
Disclaimer: I don't have any CEL but have some questions about vacuum leaks:
When I was re-installing the air box this past weekend, I noticed that the three mounting bolts with the rubber grommets could not be tighten enough to seal properly and the box had some "wiggle" to it. Would this be an issue for a vacuum leak?
When I was re-installing the air box this past weekend, I noticed that the three mounting bolts with the rubber grommets could not be tighten enough to seal properly and the box had some "wiggle" to it. Would this be an issue for a vacuum leak?
Also, when ever I fill up gas, when removing gas cap I don't feel suction or hear any "pop" sound indicating absence of vacuum. Gas cap was recently replaced. Would this also be an issue for a vacuum leak?
Rookie
Joined: Feb 2013
Posts: 66
Likes: 0
From: NY
This is a problem. Your fuel tank should be air tight. In fact, I'm surprised you're not getting a CEL based on your description. I can let my car sit several days and go loosen the gas cap and hear the pressure release. Did you put an OEM gas cap on? The gas cap must be air tight for the EVAP system to function properly.
The gas cap is generic and was replaced last month along with new A/F sensors. I figured with empty tank the pressure would be lower. Added to my todo list - will investigate further. Cheers.
EDIT: Looks like low pressure when removing gas cap is common :
https://www.clublexus.com/forums/rx-...sure-poll.html
Last edited by tarzan17; Mar 1, 2013 at 02:14 PM.
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