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Re: New Codes?? P0420
DTC P0420 relies heavily on all of the O2 sensors for checking the converter. If the sensors are slow in reacting to changes in fuel mixture, the P0420 can be set. Here's a quick test: Connect the scan tool, bring engine to operating temperature, maintain 1,500 RPM and watch the "bank 1 sensor 2" voltage. It should be remain between .2 and .4 volts. Post your results.
The HVAC problem is caused by a vacuum leak. Could be a hose, the check valve, the reservoir, the switch, or an actuator. The vacuum line from the PCV valve to the HVAC check valve is a common problem.
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