I would replace both upsteam and downsteam o2 sensors before replacing the cat. If you need the mopar part numbers, send me a pm with the last 9 of the vin. And I also have a PDF file that the dealer uses for the P0645 code. Page 1 of 2

Symptom:
P0645-A/C CLUTCH RELAY CIRCUIT
When Monitored and Set Condition:
P0645-A/C CLUTCH RELAY CIRCUIT
When Monitored: With the ignition key in the run position and battery voltage above 10.4
volts.
Set Condition: An open or shorted condition is detected in the A/C clutch relay control
circuit.
POSSIBLE CAUSES
A/C CLUTCH RLY CIRCUIT WIRING HARNESS OBSERVABLE PROBLEM
A/C CLUTCH RLY CIRCUIT WIRING HARNESS INTERMITTENT PROBLEM
FUSED IGNITION SWITCH OUTPUT CIRCUIT OPEN
A/C CLUTCH RELAY CONTROL CIRCUIT OPEN
A/C CLUTCH RELAY CONTROL CIRCUIT SHORT TO GROUND
A/C CLUTCH RELAY
PCM (A/C CLUTCH RELAY)
TEST ACTION APPLICABILITY
1 Ignition On, Engine Not Running
With the DRB, actuate the A/C Clutch Relay.
Is the A/C Clutch Relay clicking?
AIR CONDITIONING
Yes ® Go To 2
No ® Go To 4
2 Turn ignition off.
Using the schematic as a guide, inspect the Wiring and Connectors.
Were any problems found?
AIR CONDITIONING
Yes ® Repair as necessary.
Perform the Powertrain Verification Test - Ver 2.
No ® Go To 3
3 Ignition On, Engine Not Running.
With the DRB, actuate the A/C Clutch Relay.
Wiggle the Wiring Harness from the Relay to the PCM.
Did the wiggling interrupt the clicking?
AIR CONDITIONING
Yes ® Repair as necessary where wiggling caused the clicking to be
interrupted.
Perform the Powertrain Verification Test - Ver 2.
No ® Test Complete.

 

That last post is gibberish to me to be Honest master tech. The o2s look like the originals to be honest so I was gonna replace both. I was gonna get the densos ill post a link to em to make sure they are the right ones.

 

The rear:
http://m.autopartswarehouse.com/sku/....html?loc=Rear

The front:

http://m.autopartswarehouse.com/sku/...html?loc=Front

 

Yeah stick with the densos...when i needed one everyone tried selling me bosch. Ended up going to the dealer and got one for $70. Now i see that they are online

 

Ya those are 50-60 a piece

 

Thats a great deal as soon as i was told i had to go to the dealer i knew i was gonna get shafted. Glad youre getting a way better price. Luckily when i bought mine it was all i needed to pass emissions...on the last day of the month.

 

You can get them on www.rockauto.com for 1/2 the price of one from the auto parts store. Just got to wait a few days is all. I would only get DESNO or NGT sensors.

 

Awesome find hydra!

 

No problem.

Also you can google on the net and find a "rockauto coupon" that will save you the shipping like this: http://www.retailmenot.com/view/rockauto.com

 

Thanks hydra! Didn't even think of lookin on rock auto