I have a 1997 Grand Cherokee Laredo 4.0
The check engine code get the "code 21 oxigen sensor"
I've replace with an universal "the ones with 4 wires, 1 black, 1 purple and 2 whites and you have to solder the original plug on it" I've replaced and the code 21 still.

What I'm doing wrong??
Thanks in advance.

I have a 1997 Grand Cherokee Laredo 4.0
The check engine code get the "code 21 oxigen sensor"
I've replace with an universal "the ones with 4 wires, 1 black, 1 purple and 2 whites and you have to solder the original plug on it" I've replaced and the code 21 still.

What I'm doing wrong??
Thanks in advance.
HI TRY DISCONNECTING THE BATTERY GROUND CABLE FOR ABOUT 45 SEC. IF IT DOESN'T OFF REMOVE BATTERY POSITIVE CABLE FOR ABOUT 45 SECS. HOPE THIS HELPS DALE jeepman600@aol.com :smokin:

HI TRY DISCONNECTING THE BATTERY GROUND CABLE FOR ABOUT 45 SEC. IF IT DOESN'T OFF REMOVE BATTERY POSITIVE CABLE FOR ABOUT 45 SECS. HOPE THIS HELPS DALE jeepman600@aol.com :smokin:
Yes, Dale I did it,
but the problem is the check engine turns on again and a hesitate too

thanks for the reply

I have a 1997 Grand Cherokee Laredo 4.0
The check engine code get the "code 21 oxigen sensor"
I've replace with an universal "the ones with 4 wires, 1 black, 1 purple and 2 whites and you have to solder the original plug on it" I've replaced and the code 21 still.

What I'm doing wrong??
Thanks in advance.
HI, HOW MANY WIRES WERE ON YOUR ORGINAL OXYGEN SENSOR, IF IT HAD LESS WIRES OR MORE YOU MAYBE CUTTING OUT A CIRCUIT THAT WAS ON THE ORGINAL. DALE
jeepman600@aol.com :smokin:

HI, HOW MANY WIRES WERE ON YOUR ORGINAL OXYGEN SENSOR, IF IT HAD LESS WIRES OR MORE YOU MAYBE CUTTING OUT A CIRCUIT THAT WAS ON THE ORGINAL. DALE
jeepman600@aol.com :smokin:
My original sensor has 4 wires with the same colors as the replacement

I know some models have 2 O2 sensors, one b4 the Cat, and 1 in the Cat, I think, maybe urs has the same, I will check real quick and let u know

Yes, there is 2 O2 sensors in ur model, 1 b4 the Cat, and 1 after the Cat.
did u replace them both, it may be the other one, or it could be just disconnected. check that they r both plugged in.