i got burned by seller and smogger

Causes


A code P0136 may mean that one or more of the following has happened:

• Faulty O2 sensor leak in exhaust close to O2 sensor Short to voltage on O2 signal circuit
• Open in circuit resistance caused by corrosion in connector

Possible Solutions

• Replace the second oxygen sensor on bank 1 Repair open or short in signal circuit
• Clean corrosion from connector

A code P0420 may mean that one or more of the following has happened:

• Leaded fuel was used where unleaded was called for
• An oxygen sensor is not reading (functioning) properly
• The engine coolant temperature sensoris not working properly
• Damaged or leaking exhaust manifold / catalytic converter / exhuast pipe
• Retarded spark timing
• The oxygen sensors in front and behind the converter are reporting too similar of readings

Possible Solutions


Some suggested steps for troubleshooting a P0420 code include:

• Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
• Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
• Inspect the downstream heated oxygen sensor (HO2), replace if necessary
• Replace the catalytic converter