2011 Maxima p0197 Wiring schematics

A wiring diagram isn't going to help you fix this.

The P0420 code means your car's Bank 1 catalytic converter isn't working efficiently enough, triggering the Check Engine Light because the rear oxygen sensor reads similarly to the front one, indicating it's not cleaning exhaust properly.

A P0430 code means your Bank 2 catalytic converter isn't working efficiently enough, triggering the check engine light because the downstream oxygen sensor detects similar readings to the upstream sensor, indicating poor exhaust cleaning. Common causes include exhaust leaks, faulty O2 sensors, or a failing catalytic converter, with symptoms like rough idling, power loss, or failing emissions tests, often requiring diagnosis for underlying issues before replacing the expensive converter.

What it means

• Catalyst System Efficiency Below Threshold (Bank 2): The vehicle's computer sees that the catalytic converter on the side of the engine opposite the first cylinder (Bank 2) isn't converting exhaust gases effectively.

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Common Symptoms

• Check Engine Light illuminated.
• Reduced engine power or rough idling.
• Failed emissions test.
• Potential for exhaust smoke or stalling.

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The first suspect would be O2 sensors. Then the cat itself, but those are pretty reliable unless the car has LOTS of miles on it.