Ok guys I'm puzzled on this one

 

I have a client with a 05 baja... First I thought it was o2 sensors that were bad because we kept getting the p420 over and over. So a few days ago I found out that the p420 only comes on with the cruise on and ridding at 50+mph... Could it be a bad cell battery? Please hellllpppp

 

Thanks

Had a 01 forester was always puting a 420 code turned out the catt was split had a big crack right axross the middle of it also check for any exhasut leaks center donut and head flanges. Also check feul preshure regulator vacume line is good and air box is assembeld right

Not sure what you mean by bad "Cell battery"?  Do you mean a cell in the Battery?  Do you mean the CEL?  Is your Cell Phone interfering with the catalytic converter when the battery gets low?  Pretty sure that the FCC would like to know about that.

 

Seriously though, If the O2's didn't fix it, it likely needs a CAT.

I thought this might relate to a vacuum leak in the cruise control affecting the feedback loop for the cat. monitor (similar to what Ivan is saying about FPR), but doesn't a '05 model have an electronic throttle?

HAve you tried using a vacume gauge to see if the cat is functioning porperly. You can be on the hairy edge of something failing, a vacume leak, exhaust leak etc. Sometimes you have to wait for things to get worse before you can really pin down an issue. Does the CEL go out with the cruise control turned off?

Cruise drives the car at lower rpms and under more load putts more stress on system

I thought this might relate to a vacuum leak in the cruise control affecting the feedback loop for the cat. monitor (similar to what Ivan is saying about FPR), but doesn't a '05 model have an electronic throttle?

nah the 05 baja is still drive by cable... 

 

Not sure what you mean by bad "Cell battery"?  Do you mean a cell in the Battery?  Do you mean the CEL?  Is your Cell Phone interfering with the catalytic converter when the battery gets low?  Pretty sure that the FCC would like to know about that.

 

Seriously though, If the O2's didn't fix it, it likely needs a CAT.

bad cell batteries are known to give bad feed into electrical systems, but i just tested the battery and it is good

 

HAve you tried using a vacume gauge to see if the cat is functioning porperly. You can be on the hairy edge of something failing, a vacume leak, exhaust leak etc. Sometimes you have to wait for things to get worse before you can really pin down an issue. Does the CEL go out with the cruise control turned off?

no vacuum leaks nywhere... cel stays on after it comes on  even when the cruise is turned off...