Diagnosis and Dangers

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  A bad sensor will alert the vehicle's computer, triggering a "check engine" light on the vehicle's dashboard. A bad sensor typically causes engine surges. Surging over time will cause engine damage, cause an engine to stall and could lead to a driver over-throttling, creating a dangerous driving situation.
  
  

Sensor Replacement

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  GM oxygen sensors should be replaced at least every two years, as a part of regular maintenance. A sensor can be easily replaced by an amateur mechanic.
  
  

Costs and Warnings

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  A GM sensor typically costs $20 to $100 at 2010 prices, depending on the make and year of the car. GM sensors can be purchased online more cheaply than from a GM shop, but check first, as warranties generally cover the cost.