Oxygen sensor problem

[estland 3]

Hello,

 

My car has started showing check engine light while driving. The fault code is 51 which indicates an oxygen sensor.

 

When I tested the sensor the output voltage was from 0.2 to 0.8 volts. When I created a vacuum leak the voltage started slowly dropping to 0.25 volts.

 

Can the sensor still be faulty or can there be some other fault?

[petert 549]

I take it's a  Motronic DKZ? If so yes, they're very fussy about oxygen sensors.

[estland 3]

Thanks for the reply . Yes, it's a xu9jaz engine. 

 

 I cleared the fault code by disconnecting the battery lead and for one day I haven't had a warning light.

 

 I'm suspecting a "lazy" sensor as it's near 30 years old now.