Code p0420, Oxygen Sensor?

2005 PONTIAC GRAND PRIX

164,721 MILES • 3.5L • V6 • 2WD • AUTOMATIC

JOANN73

MEMBER
1 POST

The check engine came on and the code was p0420 code. I want to check the oxygen sensor with a multimeter but don't know what the ohms reading should be. Can you tell me what it should be?

Jul 30, 2022 at 11:26 PM

JACOBANDNICKOLAS

✓ASE Certified Mechanic
110,194 POSTS

Hi,

Here is a link that explains how to check/test an O2 sensor using a voltmeter/multimeter. Also, if you have a live data scan tool, you could watch the voltage signals from the sensor. It should be between 0.1v and 1.0v and jump when the throttle is pressed.

Here is the link that explains how it can be done with a multimeter:

https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor

I hope this helps. Also, in most cases, the code you have indicates the catalytic converter has failed.

Let me know what you find or if you have other questions.

take care,

Joe

Jul 31, 2022 at 12:44 PM

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