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air-fuel ratio lean code on OBD-1 diagnostic

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Old 11-23-03, 11:21 PM
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jacobking
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Default air-fuel ratio lean code on OBD-1 diagnostic

my check engine light came on along with my tract control light the other day briefly (about 5 minutes) and did so one other time the next day. i cured it both times by flooring it for a second (sounded like a good idea-it worked). anyhow, i cheked the code and retrieved code 25 (air/fuel ratio lean). what would cause this, anyone know? also, it did it both times on the freeway at low rpms when i was cruising. thanks in advance!!! (it's an sc400 with 200,000k)
Old 11-24-03, 07:26 AM
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VVT-i
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I've seen the code on the SC400 turn out to be the bad main O2 sensors. Get somebody with the scan tool and ask him to do the O2 sensor RPM check.
Old 11-25-03, 12:02 AM
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tech237
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mass air flow sensor
Old 11-25-03, 08:42 AM
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persian451
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bad o2 sensor, cant be bad MAF eventhough the manual may say that could be the problem. most likely one of the sensors after teh cat convertors
Old 12-01-03, 01:34 PM
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Faceless1
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You need to replace both air / fuel sensors (O2). Left and Right Bank BEFORE CAT. The ECU is reading a variance between sensors. You need to do both because changing only one will not erase the problem at all times.
Old 12-20-03, 09:38 PM
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tech237
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how about a vacuum leak??
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