O2 sensor heater circuits

nanoudge99

New member
Hey lads, my mate has a 2007 2.0 rx non turbo with codes p0030 and p0037 both relating to low heater circuits, when testing both sensors there is resistance between the heater wires on both sensors. The alternator appears to be failing as the headlights and interior lights flicker on idle as well as a screaching alternator. seeing as it's two separate sensors with the same problem and one is brand new. could the low voltage of the car be causing the low circuits codes for both sensors as they are mostly likely receiving less than 12v if the rest of the electronics seem to be struggling with power. Cel on only those two codes and no battery light on dash

Thanks in advance
 
Where are you based.

Read voltage from alternator see if charging


And live voltage from sensors. So signal voltage back to ecu.

Sent from my SM-N910T using Tapatalk
 
Where are you based.

Read voltage from alternator see if charging


And live voltage from sensors. So signal voltage back to ecu.

Sent from my SM-N910T using Tapatalk


We checked the signal wires also and they do give a voltage varying in the correct range when up to temps, car is running well and air fuel ratio is good also, comparing it to my impreza it is actually functioning just the heater circuits causing issues will check alternator voltage tomorrow, battery was 13v when the car was off
 
There is a 30a fuse in box under bonnet.

Not in work yet to check diagrams. Its a square pink fuse. On non turbo models if this blows will throw fault for both sensors. Normally can look ok quickly by eye. As may only be slight crack in it breaking circuit. So take good close look at it

From memory its here beside main fuse.



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