obd ii code.....'97

Hi!

My '97 JGC just gave me an error code...P0133, O2 sensor slow to respond. Do I need to just replace it, or is there something else I should try first? I assume that bank 1 is the sensor that is upstream from the cat converter (on the exhaust manifold..)

thanks!

cal

Reply to
Cal
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I'd replace the O2 Sensor. It should be the one closest to the motor. If you have an I6, it will be on the manifold. A V8 will have a Bank 1 and a Bank

2, the I6 only has Bank 1.

If there was an O2 Sensor after the CAT, then the code would be that the CAT isn't working right. I forget the specific verbiage, but the CAT has no parts that can fail, so a failed CAT is probably caused by a failed sensor. Having said that, a CAT _can_ fail, but you usually know because the main failure mode is that it gets clogged and this affects performance.

Reply to
Jeff Strickland

Thanks! I'll pick up one today, and replace it..

cal

Reply to
Cal

A 97 V8 will have 1 upstream and 1 downstream sensor. Just like a 6 cyl will.

You make this up as you go? Cat converters can and quite often do fail without plugging or rattling. If that wasn't the case, there would be no need to monitor them for efficiency. If you get a fault for a failed cat, chances are the cat is hosed. If there's a problem with the downstream sensor, you'll get a downstream sensor fault. Not a cat failure fault.

Reply to
bllsht

Yes, but Bank 1 is one side of the motor, Bank 2 is the other side. These are both before the CAT, and if there is one after the CAT, then it is not Bank 1 OR Bank 2.

Yes, you're right. CATs do fail.

But they have no moving parts, and the most likely failure is the after-CAT sensor. And the sensor is cheaper than the CAT by a wide margin. The Sensor won't always know that it has failed, it'll _think_ that the CAT is gone first.

Reply to
Jeff Strickland

Reply to
L.W.( ßill ) Hughes III

By default, if there's one O2 before the cat, it's the bank 1 upstream. Likewise, the downstream sensor will be bank 1 downstream. That's the way they are referred to by scan tools.

If you had a clue as to how the system operates, you'd know the sensor doesn't _think_ anything. It just changes voltage as O2 content changes. Alone, it can't cause a cat efficiency failure. The PCM determines whether the cat is operating properly or not, by looking at upstream vs downstream switch rates.

A brand new, perfectly operating downstream O2 sensor would be more likely to trigger a cat fault than an old worn out, slow switching sensor.

An old worn out inoperative downstream O2 sensor will trigger a downstream O2 sensor fault. NOT a cat fault.

Reply to
bllsht

Jeff Strickland wrote:>

Actually, the way GM numbers them, any of the sensors with exhaust from the #1 cyl flowing past it is considered Bank 1. Thus, the one after the cat is called Bank 1 Sensor 2.

However, if it's a dual cat setup...then you have 4 sensors, bank 1 sensors 1&2, and bank 2 sensors 1&2.

The parts guys just love trying to figure it out, because their book names them altogether differently(something like positions 1, 2 and 3).

-- Old Crow '82 FLTC-P "Pearl" '95 Wrangler YJ TOMKAT, SENS, BS#133, MAMBM, SLOB#13, DH#2

Reply to
Old Crow

If I was the engineer, I'd design the two before the cat the same, and the two after the cat the same. If it was possible to make them all the same, then that's what I'd do.

Frankly, there isn't much to an O2 Sensor, and the automaker doesn't even design them, they buy them off the shelf someplace. The main differences (besides front and rear) is the connectors, and these can easily be made uniform to avoid a half-dozen different part numbers.

Reply to
Jeff Strickland

Chrysler does the same thing. The guys who write the service books don't talk to the guys who write the parts books. One part can have 2 different names, depending on who you talk to. O2 sensor location is always tricky also. Some aren't even listed by location, just by the length of the pigtail, which is really stupid.

Reply to
bllsht

Reply to
philthy

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