Audi Workshop Service and Repair Manuals > A3 Mk1 > Power unit | Simos injection and ignition system (4-cylinder) | Mixture preparation system, electronic inj.,Gas | Checking Lambda control | Checking lambda probe heating Z19 for lambda probe upstream of catalytic converter

Test sequence

–	Unscrew protective cover -arrows- on vehicle floor.

–	Unplug 6-pin connector (black) -1- for lambda probe upstream of catalytic converter -G39-.

–	Connect multimeter between contacts 3 and 4 to measure resistance.

t	Specification at room temperature 2.5 ... 10 Ω

If specification is not attained:

–	Replace the lambda probe 1 upstream of catalytic converter -G39-.

If specification is attained:

–	Check the voltage supply to the Lambda probe heating.