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Discussion Starter #1
MY GRAND VITARA IS 2001 2.5 ENGINE. REVIEWING THE LOCATION OF THE OXYGEN SENSORS, I ONLY SEE THE TOP 2 AND DO NOT HAVE THE 2 THAT SHOULD GO AFTER THE CATALYSTS.
MY GV WORKS PERFECTLY AND HAS NO ERRORS IS THAT NORMAL ?.
 

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Your engine should be a 2.5L V6. 2 banks. So two O2 sensors after exhaust.'
There should be two after the catalytic converter.
The upstream O2 sensor is used to monitor the exhaust
and adjust the pulse width modulation of the fuel injector signal
The downstream O2 sensor is used to monitor the efficiency of the catalytic converters
Both up and down stream sensors are part of the fuel emissions system in the states.
Don't know if it is necessary in your market.

Note: In the United States, from 1991 to 1995, OBD I was used.
And from 1996 onward, OBD II was used.
 

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Only the OBD2 vehicles have O2 sensors downstream from the catalytic converters, if your car is not OBD2 it may have only two O2 sensors, or it may not have any O2 sensors at all.
 

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Are there any GVs that have a sensor downstream from the 3rd catalytic convertor (which is roughly underneath the driver’s seat (LHD))? My 2002 XL-7 doesn’t.
 

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Nope, just the 2 on each bank, pre and post main cats as far as I've seen on the V6 engines
 

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I always thought that with more or less modern cats the exhaust gases are monitored both before and after the cat, in order for the ECU to make any necessary adjustments. Apparently not ...
 

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they are theres one sensor before main cat manifold side and one after for mixture control and emissions

No need to fit additional sensors, you only need to monitor the main cat
 

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Upstream O2 sensors are used to determine fueling (what the ECU uses to make the necessary adjustments), downstream sensors are used to measure catalytic converter efficiency.
 

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Discussion Starter #9
OK friends. I rechecked the entire exhaust system and I'm sure there are only 2 sensors, one on each side and located before the converters, and nothing after them. Also check if there is an OBD2 port.
I am not a mechanic, but all this also seems strange to me, so I share it with you.
 

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OK friends. I rechecked the entire exhaust system and I'm sure there are only 2 sensors, one on each side and located before the converters, and nothing after them. Also check if there is an OBD2 port.
I am not a mechanic, but all this also seems strange to me, so I share it with you.
That sounds perfectly normal for some vehicles, some only have upstream sensors
 

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Also check if there is an OBD2 port.
The presence of the diagnostic port does not mean the vehicle is OBD2 - the port may be there but the ECU may not use the OBD2 protocols.
 

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Discussion Starter #12
The presence of the diagnostic port does not mean the vehicle is OBD2 - the port may be there but the ECU may not use the OBD2 protocols.
That seems logical to me. When I have a chance I will scan my GV and inform you.
Thank you very much.
 
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