PO430- 98 Explorrer 4.0L SOHC 2WD

ScottVA

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#1
My wife was driving my truck and was on some ice and someone pushed her into a pole. She hit the pole on the drivers' side from the front of the wheel well flare to the gas filler door. She didn't hit very hard- mostly scrapes along the quarter panel. Anyway, after this incident, the CES light was on. I took it to AutoZone where they scanned the PCM and found the PO430 code. I have tried to access the O2 sensor connectors but they are tightly tucked in between the firewall and the rear of the motor- almost completely inaccessible. I haven't been able to figure out if I'm getting correct readings. Is there somewhere that I can get step-by-step test procedures by code? Will AllData have this info? If so, I'll get a subscription and get on my way to fixing this problem.

Thanks,
ScottVA
 
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#2
Is that the only code?.....check after cat 02 sensors, and exhaust system...

one of the techs here at bat wrote this ......hope it helps...
 
  http://www.troublecodes.net/articles/catfailure/
 

oldtimer53

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#3
Catalyst (in)-effieciency code is set when the O2 sensor reading of the downstream sensor(sensor behind cat) mimics the reading of the upstream sensor. The upstream sensor should "switch" voltages (low to high) .09 to .9 range when system is running OK. The downstream sensor(once the cat is hot) should stay a steady reading, showing that all fuel and air has been burnt in the cat. If the reading of the downstream track the upstream, then the cat is "inefficient".
If you have a scanner that can display datastream information, you can watch to see what the readings are on the O2 monitor display.
An exhaust leak or a miss can sometimes falsely set this code.
If you suspect a bad sensor, try switching sensors side to side, if a funky reading moves with the sensor, then replace the sensor.
Ford cautions about blindly replacing a Cat when this code is read. This one is OK to clear and drive to check if it comes back.
 

autodr

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#4
Most likely bad cats. Which would not be related to the wreck. If it is bad cats, the light was probably about to come on anyway. Some of those older Fords have a reflash for the PCM that loosens the parameters of what the PCM deems acceptable and will sometimes get a few more miles out of freshly failing cats before the light comes back on. You can also have sluggish upstream O2s set a cat code, but that is only really when the cats are borderline to fail anyway. So if you have borderline upstreams coupled with borderline cats, then sometimes you can get lucky and fix the code with fresh upstream O2s... for a while anyway. To help make that call, a tech would need to access Mode$6 data and check the amplitude on the upstream O2s, especially the offending bank. If the amplitude is a barely-pass value, and mode $6 also shows the cats as a barely-fail value, then an O2 might help.

To show what I mean, look at these 2 mode$6 shots.

In the first one, the O2 amplitude barely passes since the "value" is just slightly above the threshold limit (higher is better here). At the same time, that same cat barely fails since the value is just barely over the threshold limit (lower is better on this one). This one set a Cat efficiency code, but might get back down the road for a little while with a new O2 only... maybe.

In the second one, no cat code is set... yet. It passes, but just slightly. It will set a cat code soon. Which is probably what your vehicle was like before the wreck... just barely passing.

BTW... both screen shots are mine, even though one clearly came off the net. That screen shot is in another PC that is down for repairs. I had to pull that shot from an article in UnderHood Service.... that was my article so there is no copy write issues here.

[attachment deleted by admin]
 
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#5
ScottVA said:
My wife was driving my truck and was on some ice and someone pushed her into a pole. She hit the pole on the drivers' side from the front of the wheel well flare to the gas filler door. She didn't hit very hard- mostly scs along the quarter panel. Anyway, after this incident, the CES light was on. I took it to AutoZone where they scanned the PCM and found the PO430 code. I have tried to access the O2 sensor connectors but they are tightly tucked in between the firewall and the rear of the motor- almost completely inaccessible. I haven't been able to figure out if I'm getting correct readings. Is there somewhere that I can get step-by-step test procedures by code? Will AllData have this info? If so, I'll get a subscription and get on my way to fixing this problem.

Thanks,
ScottVA
Yes All data has a lot of good info on it.
But you also need a good scanner and volt/ohm /meter.

One thing to start with is make sure the engine is running up to par.
A rich running engine or cylinder miss can cause a cat code.

Good luck with it.
Crunch

Little info below.
DTC P0420, P0421, and P0430 & P0431: Check Possible Cause Of Misfire DTC P0420 and P0421 indicate bank one catalyst system efficiency is minimum requirement. DTC P0430 and P0430 indicate 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 is not present, go to next step. If misfire code 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. 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 engine and 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.
 

ScottVA

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#6
WOW!!! Lots of good info. Thanks a bunch guys. I think this issue may be a little over my head- especially since I don't have a scanner or oscilliscope. I just have a cheap, rinky-dink multimeter. May main problem with this, I guess, is accessing the O2 connectors. They are tucked deep between the firewall and the rear of the engine. Now, I'm kind of a skinny guy but I'm not that skinny!!! :D I'll try it again next week while I'm off work (yeah, I'm one of those that gets the whole week off ;D) and let you know what I find.

Crunch- I'm sure it's not a problem, but can I print out your reply for reference while I try working on this again?(Just CMA)

Thanks all,

ScottVA
 
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#7
ScottVA said:
WOW!!! Lots of good info. Thanks a bunch guys. I think this issue may be a little over my head- especially since I don't have a scanner or oscilliscope. I just have a cheap, rinky-dink multimeter. May main problem with this, I guess, is accessing the O2 connectors. They are tucked deep between the firewall and the rear of the engine. Now, I'm kind of a skinny guy but I'm not that skinny!!! :D I'll try it again next week while I'm off work (yeah, I'm one of those that gets the whole week off ;D) and let you know what I find.

Crunch- I'm sure it's not a problem, but can I print out your reply for reference while I try working on this again?(Just CMA)

Thanks all,

ScottVA
ScottVA
Feel free to print it out for your own use.

But I do not know if Bat has copy rights on stuff posted in the forums or not.
So beware about copying to or reposting anything back on the net.
Good Luck
Crunch