Lean issue

Sgt_smoku

Member
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2003.5 mazda protege
He guys having a wierd lean issue. Scan tool with car off shows both o2 sensors functioning properly (by voltage) while cars running o2b1s1's voltage will sit at idle 0.000-0.005 while o2b1s2 will sit 0.415. Through a raise in rpm o2b1's voltage will not change higher then .0015. Osb2 will change with throttle. Car was having a idle issue and 99% of it was cleared up with a new maf. New wires, plugs, ignition coils. Rpm at idle is holding 706-710rpm theres no loss in power and she runs through that rpm band really smooth down the road. Current temp outside is 59degree. And all other live data shows good running condition. Is there any suggestions on why os in bank 1 is showing lean and should i be conserned? I can give more info if needed.
 
update.

not a lack of fuel issue she patching well into 3rd gear still, decided to pull the o2 and it was rather sooty. cleaned it off, cleaned the connector and put it back in. tested voltage key in on position, engine off good voltage. turned motor on, live data it was sitting 0.250ish and then just slowly fell on its face to a 0.000-0.005 again within mins..
 
Update

It was bad o2. Bought i new one put it in. No longer running open loop fault and proper live data voltage reads.
 
Thanks for the info. It may come in handy. I finally had to replace a small diameter vacuum hose after the end kept splitting. The check engine light was due to a lean condition - vacuum leak.
 
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