Code 420

Discussion in 'GM Powertrain' started by Oscarvan, Feb 1, 2011.

  1. Oscarvan

    Oscarvan Rockstar

    2002 Suburban 1500

    Which I think means: Bank 1, efficiency below threshold.

    So it's the cat or the down stream 02 sensor, right?

    Any way to test the sensor? If so how? Special tools required?

    Thanks for any insight.
  2. Oscarvan

    Oscarvan Rockstar

    Good idea, will try that.

    Can someone confirm that bank 1 is the drivers' side?

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