Monitoring oxygen sensor signal switching frequency and amplitude is the key to a quick functional test of the entire closed loop control subsystem. The check can be performed as follows:
• Start engine and allow it reach operating temperature
• Make sure all accessories are off
• Run engine at 2500 rpm for at least two minutes to ensure 02 sensor is at normal operating temperature
• 02S signal frequency should be at least eight cycles in ten seconds (0.8 hz) in order to ensure efficient catalyst operation.
• Also, signal amplitude should consistently exceed 550 mv on the rich swing and fall below 400 mv on the lean swing. If the sensor is degraded, either signal frequency or amplitude or both will be effected.
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