Code P0430???

My friends 99 Explorer,5.0,90k,had a code P0430 Catalyst System Efficiency Below Threshold Bank(Bank 2).Does anyone have any ideas on what the most likely cause of the problem is, I'm guessing that it is either
1)Worn out cat on that side
2)Bad O2 sensor on that side
3)Maybe needs tune and cat is getting too many unburned hydrocarbons.
We cleared the code 3 days ago and it hasn't come back yet so I'm not going to act on it unil/if it comes back.Also does any one know wich bank is #2 I would assume it's the passenger side but thats just a guess.Any info would be appreciated because I have not dealt with this type of problem before.
Thanks
Unbe

pretty sure bank two is the side with #2 plug. fords confuse me cuz i know theyre opposite chevy and dodge and requires me to think :P. and id go with #3. the code shows the o2 is doing its job. the cat is worn out and is probably getting too much gas into it from somewhere. a lot of times as long as everything checks out and you replace the cat itll last quite a while. a tuneup at 90k wouldnt be a bad iddea at all and id also do a lot of other maintenance it probably needs.

My friends 89 Explorer,5.0,90k,had a code P0430 Catalyst System Efficiency Below Threshold Bank(Bank 2).

Are you sure it is an 89, or do you mean 99? Bank 2 converter is on the drivers side. Need PID readings to determine if it is O2 sensor, excessive fuel, too little fuel, or exhaust leak.

a catalyst efficiency code is not an o2 sensor code, there is a separate code for that. the code sets when the rear o2 switches too much. PIDs would help figuring out what killed the cat tho.

[QUOTE=way2old]Are you sure it is an 89, or do you mean 99?
My mistake it was a 98 or 99 ,I went back and edited ,thanks for catching that.
Unbe

Thanks RahX and way2old for the info.
Unbe

Unbe
Way2old is steering you in the right direction.
Go with what he is telling you.
And remember a code 420/430 does not say the cat is bad. you need to check it out. And if it is bad there is a 8 year 80k emmision warranty on them.
What is your mileage and tune up history?
Sorry I missed the 90K you posted in first post. You are out of warranty unless calf or extended warranty.
But 90K is a goodd time to be checking the tune up end.
Here is a link on codes 420/430.
http://www.troublecodes.net/articles/catfailure/
MT

Also some info.
DTC P0420, P0421, P0430 & P0431: Check Possible Cause Of Misfire DTC P0420 and P0421 indicates bank one catalyst system efficiency is minimum requirement. DTC P0430 and P0430 indicates bank 2 catalyst system efficiency is minimum requirement. Possible causes are as follows: Use of leaded fuel. Oil contamination. Cylinder misfire. Fuel pressure too high. HO2S sensor improperly connected. Damaged exhaust system component. Faulty ECT sensor. Faulty HO2S. Ensure ignition timing is correct. Retrieve all Continuous Memory DTCs. If misfire code(s) is not present, go to next step. If misfire code(s) is present, isolate cylinder and repair as necessary. Check HO2S Monitor DTCs If DTCs P0136, P0138, P0140, P0141, P0156, P0158, P0160, or P0161 were present in step 1), service as necessary before continuing. If none of these codes are present in step 1), go to next step. Check ECT Sensor DTCs If DTCs P0117, P0118, P0125 or P1117 were present in step 1), service as necessary before continuing. If none of these codes are present in step 1), go to next step. If any codes except P0420, P0421, P0430 and/or P0430 were present in step 1), service as necessary before continuing. If no codes except P0420 and/or P0430 were present in step 1), go to next step. Check Rear HO2S Wiring Harness Turn ignition off. Ensure HO2S wiring harness is correctly routed and connectors are tight. Repair or replace as necessary. If wiring harness and connectors are okay, go to next step. Check Fuel Pressure Turn ignition off. Release fuel pressure. Install fuel pressure gauge. Start engine and allow to idle. Note fuel pressure gauge reading. Increase engine speed to 2500 RPM and maintain for one minute. For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. If fuel pressure is as specified, go to next step. If fuel pressure is not as specified, go to CIRCUIT TEST HC . Check For Exhaust System Leaks If exhaust system leaks, it may cause catalyst monitor efficiency test to fail. Inspect exhaust system for cracks, loose connections or punctures. Repair or replace as necessary. If exhaust system is okay, go to next step. Check For Exhaust System Restrictions Inspect exhaust system for collapsed areas, dents or excessive bending. Repair or replace as necessary. If exhaust system is okay, go to next step. Ć Check Manifold Vacuum Install tachometer. Connect vacuum gauge to intake manifold vacuum source. Start engine and raise engine speed to 2000 RPM. Manifold vacuum should rise to more than 16 in. Hg. If manifold vacuum is okay, go to next step. If manifold vacuum is low, go to step 11). Leave tachometer and vacuum gauge connected. Start engine and raise engine speed to 2000 RPM. On a non- restricted system, manifold vacuum should quickly rise to normal range as increased RPM is maintained. On a restricted system, manifold vacuum will slowly rise to normal range as increased RPM is maintained. If manifold vacuum is okay, no indication of exhaust leak or restriction has been detected and testing is complete. If manifold vacuum is low or slow to respond, go to next step. Leave tachometer and vacuum gauge connected. Remove exhaust pipe from exhaust manifold. Start engineand raise engine speed to 2000 RPM. If manifold vacuum is now okay, fault is downstream from exhaust manifold. Reconnect exhaust pipe to exhaust manifold and go to next step. If manifold vacuum is still low or slow to respond, fault is in exhaust manifold or intake manifold gasket. Repair or replace as necessary and repeat QUICK TEST. Leave tachometer and vacuum gauge connected. Disconnect muffler/tailpipe assembly from rear of catalytic converter. Start engine and raise engine speed to 2000 RPM. If manifold vacuum is now okay, fault is in muffler/tailpipe assembly. Repair or replace as necessary and test drive vehicle to verify elimination of symptom. If manifold vacuum is still not okay, fault is in catalytic converter. Repair or replace as necessary. Check tailpipe/muffler assembly for debris from catalytic converter. Test drive vehicle to verify elimination of symptom.

MT-2500
Thanks for the info it will be quite useful when this problem comes back.I went from knowing nothing about this code to having quite a few things to check and in what order to check them.Thanks again
Unbe

You are welcome.
Glad the info helped.
That is a hard code to check out and find the root cause.
But remember the tune up end is first thing to look over and like Way2old says the PCM PID reading will tell you a lot about it.
Let us all know how it goes.
Good Luck
MT

If you have a 5.0 Thunderbolt V8, and are continually getting the MIL with codes P0420, and/or P0430, and the engine is not missing, or dumping too much fuel, you may want to consider looking into getting the PCM recalibrated to the latest specs. (WDS release B28.3). There is a chance that the original calibration had a band that was too tight to accomodate an older vehicle, showing a false failure. Even though you need to see a service center with a STAR Tester, this is much cheaper than having to buy two new HEGOs, or two new catalytic converters. This is covered under a TSB from 2004: 04-7-5.

Great Vehicles, and Good Luck !