Oxygen Sensor/Check Engine Light

[quote:53a2eb6a0d="bass3688"]About a year ago I bought a 1997 Ford Probe and as of right now it has approx. 116,000 miles on it. It is the 4 cyl. 2.0 liter automatic transmission. The check engine light has been on practically since I bought it and I recently read the codes as to why it was on and it told me it was PO421 Warm up catalyst efficiency below threshold (bank 1). Well I read more into that and found out it was the oxygen sensor, but was wondering if there is more than one oxygen sensor on the car and if so where the bank 1 one is so i can change it. The car also jerks a lot when shifting into drive and reverse and i was wondering if this has anything to do with the sensor. Thanx for your help.[/quote:53a2eb6a0d]

Here's more about oxygen sensors and what/where certain banks/sensors located.

On a scan tool, the downstream sensor on a four or straight six cylinder engine with single exhaust is typically labeled Bank 1, Sensor 2. On a V6, V8 or V10 engine, the downstream O2 sensor might be labeled Bank 1 or Bank 2, Sensor 2. If a V6, V8 or V10 engine has dual exhausts with dual converters, the downstream O2 sensors would be labeled Bank 1, Sensor 2 and Bank 2, Sensor 2. Or, the downstream oxygen sensor might be labeled Bank 1 Sensor 3 if the engine has two upstream oxygen sensors in the exhaust manifold (some do to more accurately monitor emissions).

Get a 5gas analysis it will tell whether the Cat is doing its job and where the cause is.

7 codes on the car and it seems to be jerking alittle and acts like it isnt getting the gas. transmission seems to shiftintg very good

Verify that your o2 sensors are working. Give it a large vacuum leak and see if your o2 sensor 1 and 2 should drop down to 100 mv by adding fuel it should rise to 900 mv. Once you verify that the 2 o2 sensors are working you can use them to check the cat. @ 3000 rpm or driving @ a hi speed the front o2 should be switching from rich to lean. 200 mv to 900 mv. If the rear o2 is switching as quick as the front o2 your cat has failed and can't store oxygen