So, I've had the PO432 error for quite a while now on my '07 JK, 111k miles. It goes off and on for the last few months, and I haven't seen too much of a change until the last few weeks where I've noticed my MPG has dipped a bit (approx. 1 MPG) and a slight loss in acceleration. The one shop I took it too, said it would be pretty expensive just because of how it's all connected.

Any ideas to resolve this without a ton of expense? I'm in a non-inspection state, so I'm open to any options as long as it doesn't hurt the vehicle long term.

 

Are you sure you are getting P0432? That's not a valid code for the JK, according to the service manual.
I know people have had their JKs throw invalid codes when there was nothing really wrong.

The drop in mileage may be due to winter blend gasoline, if they make it in your area.

If you are getting P0430, here is some information for that code. There are many possible causes before you go to the expense of changing the cat. Engine Mechanical has a long list of its own.

Bank 2 is the left side, as viewed from the driver's seat.

[h=2]P0430-CATALYST EFFICIENCY (BANK 2)[/h]

Theory of Operation

The State of Change (SOC) catalyst monitor uses the signals from both the upstream and downstream O2 sensors to detect aging of the catalyst. Based on the fact that when a catalyst ages, it loses some of its Oxygen Storage Capacity (OSC). As a result, part of the untreated exhaust gases can breakthrough the catalyst and causes the downstream O2 sensor to deviate from its neutral (Stoichiometric) position. By observing the activities in the downstream O2 signal, the degradation level of catalyst can be detected. In general, the higher the downstream O2 sensor SOC value, the more exhaust gas breakthrough and the lower the OSC of the catalytic converter.

• When Monitored: ECT above 70° C (158° F), engine RPM between 1400 and 2300, vehicle speed between 64 and 96 kph (40 and 60 mph), and engine run time greater than 3 minutes.
  
• Set Condition: If the final State of Change index is within the calibrated fail threshold. Two trip fault. Three good trips to turn off the MIL.

[TABLE]
[TR]
[TD="bgcolor: white, align: center"]Possible Causes
[/TD]
[/TR]
[TR]
[TD="bgcolor: white"]O2 RETURN UPSTREAM CIRCUIT SHORTED TO GROUND
[/TD]
[/TR]
[TR]
[TD="bgcolor: white"]O2 RETURN DOWNSTREAM CIRCUIT SHORTED TO GROUND
[/TD]
[/TR]
[TR]
[TD="bgcolor: white"]O2 RETURN UPSTREAM CIRCUIT OPEN
[/TD]
[/TR]
[TR]
[TD="bgcolor: white"]O2 RETURN DOWNSTREAM CIRCUIT OPEN
[/TD]
[/TR]
[TR]
[TD="bgcolor: white, align: left"]EXHAUST LEAK
[/TD]
[/TR]
[TR]
[TD="bgcolor: white, align: left"]ENGINE MECHANICAL CONDITION
[/TD]
[/TR]
[TR]
[TD="bgcolor: white, align: left"]AGING O2 SENSOR
[/TD]
[/TR]
[TR]
[TD="bgcolor: white, align: left"]CATALYTIC CONVERTER
[/TD]
[/TR]
[/TABLE]

 

Double check that code because as mentioned previously it does not show up on the diag charts. If you can get us the correct code post it up and we will be able to help.

 

My mistake, it is 430, so would O2 sensors be the first step to see if I can correct the issue without pulling the cats and y pipe out?

I know that's the more economical route, just not sure a bad 02 sensor would cause a bit of a drop (not a huge drop) in acceleration and roughly 1.5 MPG drop. If it is the cat, what are the most economical options in a state with no emissions/inspection check?

 

That code is isolated to bank 2. Possible faults are an exhaust leak, faulty o2 sensor, or faulty cat.

Inspect the entire exhaust before the cat for leaks. If everything looks OK you can try to replace the primary o2 sensor but that is just throwing parts at the problem.

If none of that works then you likely have a faulty cat.