P0420 and P0507, 2003 v40 107,700 miles

Post by **zulu-v40** » 05 Sep 2011, 15:39

Replaced idle air control valve last month with new OEM part and new OEM gasket.
Changed oil last week and noticed something leaking - just in front of catalytic converter. I've repeatedly checked the oil since, and it is not leaking. Car is no longer leaking in that spot. Could it have been condensation/h20 from a/c?

This morning I started the car, which sounded a bit rough, and the CEL lit up. I took the car to Auto Zone and the P0420 and P0507 codes were pulled.

P0420: Catalytic system efficiency below threshold (bank 1) x2
P0507: Idle air control system RPM higher than expected x2

Could the two be related?

Recently had a smoke test done and there were no leaks. Also cleaned the MAF sensor. Also replaced the EVAP purge valve. Also briefly cleaned throttle body while still attached (wasn't very dirty or gunked up at all). That leaves a faulty PCV valve, damaged/dirty/defective throttle body, or a failed EVAP system as possible causes for the P0507 code. Not sure what to do.

As for the P0420, which oxygen sensor is considered to be bank 1? Any pointers on removing and replacing? Any advice?

Post by **zulu-v40** » 06 Sep 2011, 11:49

Update: Drove to work today. The car (auto trans) seems to struggle to shift gears. It continues to rev too high instead of shifting. The tachometer will hang around 2,000 RPM and seems to jerk when finally shifting. As it warms up the problem seems to lessen in severity. I'm going to have the codes checked again today after work.

Post by **zulu-v40** » 06 Sep 2011, 18:23

Can anyone share the VADIS instructions for replacing the oxygen [or lambda] sensors specific to my vehicle?

Post by **zulu-v40** » 13 Sep 2011, 07:36

I ordered a BOSCH front oxygen sensor through FCPEuro. It'll be here tomorrow. I'm still looking for instructions on how to remove and replace the sensor. I don't want to replace it without knowing torque specs. etc.

Post by **zulu-v40** » 19 Sep 2011, 07:30

UPDATE: I replaced the front O2 sensor and reset the code along w/ the fuel map. After a day of driving, the P0420 code showed up again. Could this actually indicate that the rear O2 sensor needs to be replaced as well? I used a brand new BOSCH OEM sensor.

Post by **zulu-v40** » 26 Sep 2011, 20:18

UPDATE 9/26: Tonight, I replaced the rear O2 sensor with a brand new BOSCH OEM part. Upon reconnecting the battery the P0420 code persisted. I took the car to autozone and had them clear the code. After a brief test drive the code has yet to resurface. With both O2 sensors replaced the car seems much peppier while driving.

Tools required:
1/2 drive socket wrench
Oxygen Sensor socket from NAPA - $16 (has opening to accommodate a bit of wire)
High temp. anti-seize from NAPA - $1 (comes in a stick, apply it to sensor threads like chapstick)
Needle nose pliers (to rip out plastic anchors attached to sensor leads)
Wrench to remove battery connector (sizing varies)

When looking down into the engine bay, the first sensor attached to the top of the catalytic converter is the front sensor, or bank one. The second sensor attached to the side of the catalytic converter, best accessed from underneath the engine, is bank two. The leads for the sensors are shielded in a light yellow fabric. Follow the leads to a black cover. After removing the cover, one will find the electronic connectors for the sensors, which are removed by depressing small metal releases.

Post by **zulu-v40** » 05 Oct 2011, 06:13

UPDATE 10/05: I've now replaced the thermostat, electronic coolant temperature sensor, and both oxygen sensors. The P04020 code has gone away. Or has it...

Post by **zulu-v40** » 16 Oct 2011, 23:08

UPDATE 10/16: P0420 Code returned. Removed catalytic converter with help of PB Blaster. Then soaked cat in a 5 gallon bucket in detergent over night (combination of dish soap, laundry detergent, dishwasher soap, and bar keeper's friend). Next morning, rinsed it thoroughly with the shower head. Rinsed it w/ some mineral spirits. Rinsed it some more w/ water. Dried it w/ blow dryer. Reattached catalytic converter. Coated all threads w/ high temp. anti-seize. Added 1 gallon of laquer thinner to a 1/2 full tank of gas. Drove 130 miles, doing my best to keep engine revolutions at 2500. Stopped for some mediterranean food. Started car back up and the code cleared. Vindicated!!

Post by **Choguy03** » 17 Oct 2011, 07:25

Is this a know method to clean the cat? It sounds interesting.

Post by **zulu-v40** » 17 Oct 2011, 18:44

I found out about the method in a youtube video. Youtube is the last place I thought I would find a solution. It sounded questionable and potentially dangerous, but it worked really well for me. The car drove pretty well today. I drove around town all day. Here's a link to the video, which is actually pretty funny: youtube.com/watch?v=5icTmYItwiE