O2 Sensor Question
- Thread starter stangrulez
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squeak93
15 Year Member
The autozone guy is correct. Bank one is the pass side. (so you have a driver side issue since its bank two) and sensor one is pre cat, sensor two is post cat (or down stream by trans tail shaft if you've removed the cats).
Mineral4.6
Member
- Mar 17, 2015
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Interesting I was under the impression that bank 1 was upstream and bank 2 was downstream.
Also when I've pulled codes and had bad down stream it said system efficiency below threshold bank two. But didn't call out sensor one or sensor two.
Also when I've pulled codes and had bad down stream it said system efficiency below threshold bank two. But didn't call out sensor one or sensor two.
wmburns
SN Certified Technician
Your opening post says, "I need to replace bank 2 sensor 1 oxygen sensor". As squeak93 as stated, bank 2 is the driver's side. Sensor 1 is upstream.
The DTC calling out "system efficiency below threshold bank two" is the DOWNSTREAM O2 sensor. This DTC could never apply to the upstream O2 sensor.
HOWEVER, in the vast majority of cases the DTC calling out the downstream O2 sensors does NOT indicate a problem with the down stream O2 sensor. The problem is with the cats or the sensors supporting the motor's operation.
IMO if you insist on replacing an O2 sensor as a trouble shooting step, your $$ is better spent on the upstream O2 sensor as it will actually affect the motor's operation. If the DTC continues THEN replace the down stream O2 sensor with the sensor that was removed earlier. This gives you a "two for one" trouble shooting bang for the buck.
There's a saying that goes, "cats never die. They are murdered". What that means is a cat converter rarely go bad on their own. The are killed by conditions external to the cats. For example"
The DTC calling out "system efficiency below threshold bank two" is the DOWNSTREAM O2 sensor. This DTC could never apply to the upstream O2 sensor.
HOWEVER, in the vast majority of cases the DTC calling out the downstream O2 sensors does NOT indicate a problem with the down stream O2 sensor. The problem is with the cats or the sensors supporting the motor's operation.
IMO if you insist on replacing an O2 sensor as a trouble shooting step, your $$ is better spent on the upstream O2 sensor as it will actually affect the motor's operation. If the DTC continues THEN replace the down stream O2 sensor with the sensor that was removed earlier. This gives you a "two for one" trouble shooting bang for the buck.
There's a saying that goes, "cats never die. They are murdered". What that means is a cat converter rarely go bad on their own. The are killed by conditions external to the cats. For example"
- Excessive oil in the exhaust
- antifreeze in the exhaust
- mixture too rich
- mixture too lean
- exhaust too hot perhaps from a non working EGR system.
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