Cross Count Illustration
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Cross count
Cross count is the speed at which an oxygen sensor can oscillate between a rich to lean air/fuel mixture (or lean to rich). The faster the cross counts, the more accurate the ECU is able to adjust the air/fuel ratio. A new oxygen sensor will have a cross count of 50 to 100 milliseconds (Apx. 1/20 of a second). An aging oxygen sensor may have a cross count as slow as 500 milliseconds (one half second) although this sounds fast, in the world of electronics, this is slow. If the sensor has a slow cross count, the ECU does not receive updates fast enough to efficiently manipulate the fuel flow through the injectors. An oxygen sensor with a sluggish cross count may not be easily identifiable, it may appear to be operating properly as your check engine light isn’t on and a diagnostic check may not indicate a fault code, but you may notice poor performance and reduced gas mileage. |
