Oxygen sensor problem?
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Driver School Candidate
Joined: Oct 2012
Posts: 47
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From: Kuala Lumpur
Oxygen sensor problem?
Hi, my 1996 ls400 (97000 miles) occasionally seems to idle too low ie below 200rpm and then stalls. When it does this it runs rich where black smoke comes out.
However when i restart it, it starts up fine and revs freely. And then it idles normally for a few minutes before dropping again into low idle.
Driving around is fine and power seems to be normal.
There's no check engine light or anything. Could this be a sign that the oxygen sensors need replacing?
However when i restart it, it starts up fine and revs freely. And then it idles normally for a few minutes before dropping again into low idle.
Driving around is fine and power seems to be normal.
There's no check engine light or anything. Could this be a sign that the oxygen sensors need replacing?
CL Community Team
Joined: Aug 2011
Posts: 4,172
Likes: 1,006
From: Japan
I don't think it's an oxygen sensor problem. The ECU detects failed oxygen sensor checking the output voltage and the time interval of it and the engine check light is turned on.
Judging from your symptoms, I think your problem may be caused by the clogged or failed IACV.
Judging from your symptoms, I think your problem may be caused by the clogged or failed IACV.
+1 Have you ever had the throttle body pulled out and cleaned? If not, it is probably full of gunk.
Lexus Champion
Joined: Dec 2011
Posts: 4,078
Likes: 87
From: Birmingham, AL
yes, clean throttle body as Lavrishevo mentions, or at least the butterfly portion, if that doesn't fix the idle the then it is almost always the Idle Air Control Valve (IACV) bearings as Yamae mentioned or else failing ECU capacitors
there is a test in the service manual to verify correct IACV operation - you apply battery power to the correct pins and watch the plunger move - there is also an integrity test of the IACV coils
there is a test in the service manual to verify correct IACV operation - you apply battery power to the correct pins and watch the plunger move - there is also an integrity test of the IACV coils
Last edited by LScowboyLS; Jul 28, 2013 at 05:31 PM.
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