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Home >> Volkswagen >> 1991 >> Jetta L4-1781cc 1.8L SOHC >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Air Flow Meter/Sensor >> Description and Operation >> C.O. Adjustment Screw
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C.O. Adjustment Screw

Digifant CO Adjustment Screw:





The CO Adjustment Screw is located on top of the air flow sensor and can only be reached or adjusted after removing the anti-tampering plug in the top of the air flow sensor housing. This small plug is removed by drilling a 3/32 in. (2.5 mm) hole in the top of the plug and threading a screw into the plug so it can be extracted with pliers.

With the plug removed adjustment is made using a 5 mm hex wrench. Turning the CO Adjustment Screw clockwise makes the mixture richer (higher % CO). Turning the CO Adjustment Screw counter-clockwise makes the mixture leaner (lower % CO).