Kid's 4 cylinder Toyota 2.7L 1997 4Runner 2WD with 133K miles triggered an SES today.
My code reader indicates P0133 only.
Googling implicates "Oxygen Sensor Circuit Slow Response (Bank 1, Sensor 1)"
A description appears to be:
P0133 means the upstream oxygen sensor on bank one is not responding as quickly as it should to changes in oxygen levels in the exhaust.
The usual causes of this is an oxygen sensor that is worn out or contaminated.
We have the factory shop manual and the Chilton manual - but we have never worked on an oxygen sensor so we ask advice before we tackle this job.
Q1: Do you think an oil leak at the locations above can contaminate an 02 sensor?
Q2: Do you generally remove them in pairs?
Q3: Any other advice for diagnostic tests?
Note: We will continue googling - so this is one step in our quest.
Found section 4-9 in the Chilton manual which explained oxygen sensor behavior; they mentioned a "backprobe" for voltage, which I assume is we nick the wire insulation somehow. Any advice on how to "backprobe".
Also we looked on the passenger side for the oxygen sensor and wire. Maybe it's under the shield? Do these pictures show it to you?