Hi all. 2000 Vert, 6-spd, stock, 90,000 miles. CEL came on yesterday. DTC is p0430 - Catalyst System Low Efficiency, Bank 2

How likely is it that the sensor itself is bad? Or more likely the Cat Con is pooched? I can try a new sensor easy enough, just wondering what the forum wisdom was. Also, where is this sensor physically located - aft of the converter, but which exhaust?

Thanks!

Jason

 

Jason

Have you tried to just clear the DTC and see if it comes back. Try that first.

Beg, borrow or purchase a laser infred temp sensor and compare the operating temp of each cat. It should be able to read at least 600 Deg.

CAT temp should be the same bank to bank. Remember, you have TWO small PUP cats (located directly off the exhaust manifolds) and two main CATs in the tunnel area.

Measure the temp of each cat. They should be very close to the same on each side if there working correctly.

If the cats are operating at normal temp, you could swap the O2 sensors side to side and see if the problem stays on the same side or switches sides.


BC

 

Hi Bill, thanks for the info. I had cleared the code, comes back right away. I think I will swap the sensors first, and if the code doesn't travel, there's a chance it is the cat itself.

Thanks!

Jason

 

I'm getting this same error, yet when put on a CA Emissions machine, it passes with flying colors? I have swapped sensors from side to side without a change in reported codes. The error was intermittent for months, but is now constant. Because I still pass state emissions tests, could the computer be incorrectly reporting the error, or is there something else I might be able to look to, instead of getting into a game of trial and error with cats? Any advice would be appreciated.

 

Sometimes the emissions status will allow one error and still pass. As long as you pass, thats good.

 

I cannot pass with a Service Engine light on. The emissions part passed by I have to correct the error. Any ideas?

 

Have that error TUNED OUT. Most tuners will tune something out for a small fee. If you have a good tuner that you frequent for your tuning needs, he may just do it for free.

Bill

 

Barring tuning it out, what could be the cause of this error? I'd rather correct it, if possible (oh, and it doesn't end up costing an arm and a leg!). I mean, does the error REALLY mean something is wrong with the cat (on the left side, I think it is, though not entirely posivitve which side)? Like, if I replace the cat and clear the code, would that really be the problem, even though the emmissions level itself may be within limits?

Thanks again.

 

Hey, Bill, I don't know if you remember, but you've given me some advice on electrical stuff before, specifically when I had a front wheel sensor connection issue, and more recently when a friggin' rat got under my battery and ATE THE COMPUTER WIRES!

So, I wanted to run something by you: I swapped 02 sensors from right to left, but the error did not move from one side to the other, and I can't help but wonder if maybe, just maybe, there might be a connection issue in the harness somewhere. I was thinking of taking an ohm meter, touching one probe to each wire (don't know how many there are) in the connector end of the harness and touching the other probe to ground. I shouldn't see any opens, right? And, if I do, then it could be the wiring somewhere, right? Or, is there a better way to rule out a harness?

BTW, does the 0430 mean driver or passenger side?

Thanks.

 

Lets see if we can figure this out:

DTC P0420 or P0430
Circuit Description
In order to maintain low emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx), the engine controls system uses a 3-way catalytic converter. The catalyst within the converter promotes a chemical reaction, which oxidizes the HC and CO that are present in the exhaust gas. This reaction converts these chemicals into harmless water vapor and carbon dioxide. The catalyst also reduces NOx, converting NOx into nitrogen. The powertrain control module (PCM) monitors this process using heated oxygen sensor (HO2S) bank 1 sensor 2. HO2S bank 1 sensor 2, located in the exhaust stream past the 3-way catalytic converter, produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalyst's ability to effectively convert the exhaust emissions. If the catalyst is functioning correctly, the HO2S bank 1 sensor 2 signal will be far less active than the signal that is produced by HO2S bank 1 sensor 1. This indicates that the 3-way catalytic converter's oxygen storage capacity is below an acceptable threshold.

The PCM performs this diagnostic during idle. When the conditions for running this DTC are met, the following conditions occurs:

The PCM captures the current rear HO2S rich-to-lean status.
The air-to-fuel ratio transitions from rich to lean or from lean to rich, depending on the capture rear HO2S rich-to-lean status.
The air-to-fuel ratio transitions a second time opposite the first air-to-fuel ratio transition.
The PCM captures the response time of the front and rear heated oxygen sensors when the air-to-fuel ratio transitions occur. The HO2S response time goes from less 300 mV to more than 600 mV, and from more than 600 mV to less than 300 mV.
The PCM measures the time it takes the rear HO2S voltage to cross a reference rich-to-lean threshold, minus the time it takes the front HO2S voltage to cross the same rich-to-lean threshold. The difference between the front HO2S time and the rear HO2S time is the oxygen storage capacity of the catalyst. This DTC sets if the time exceeds a predetermined threshold.
Conditions for Running the DTC
DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0128, P0131, P0133, P0134, P0135, P0137, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0157, P0158, P0160, P0161, P0171, P0172, P0174, P0175, P0200, P0300, P0335, P0336, P0341, P0342, P0343, P0351-P0358, P0410, P0440, P0502, P0503, P0506, P0507, P0606, P1120, P1133, P1134, P1153, P1154, P1220, P1336, P1415, P1416, or P1441 are not set.
The intake air temperature (IAT) is more than -7°C (19°F), but less than 75°C (167°F).
The barometric pressure (BARO) is more than 74 kPa (10.7 psi).
The engine is operating.
The engine coolant temperature (ECT) is more than 75°C (167°F), but less than 117°C (243°F).
Since the end of the last idle period, the engine speed is more than 850 RPM for a minimum of:
17 seconds for manual transmissions
27 seconds for automatic transmissions
The closed loop fuel control is enabled.
Conditions for Setting the DTC
The PCM determines if oxygen storage capability of the catalytic converter has degraded to less than a calibrated threshold.

Action Taken When the DTC Sets
The malfunction indicator lamp (MIL) is turned ON.
A DTC is stored in memory.
The Freeze Frame/Failure Records are stored.
The Failure Records are updated after the first failure of each ignition cycle.
Conditions for Clearing the MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.
Test Description
The number below refers to the step number on the diagnostic table.

Before you replace the 3-way catalytic converter, correct any conditions which may have damaged the catalyst.

Step
Action
Yes
No

1
Did you perform the Diagnostic System Check-Engine Controls?
Go to Step 2
Go to Diagnostic System Check - Engine Controls

2
Are any other DTCs set?
Go to the applicable DTC table
Go to Step 3

3
Check for the following conditions:

Verify that the 3-way catalytic converter is an original equipment part.
Inspect the 3-way catalytic converter for damage from the following conditions:
Dents
Severe discoloration caused by excessive temperatures
Holes
Other conditions
Ensure that an internal 3-way catalytic converter rattle that is caused by a damaged catalyst is not present.
Inspect the exhaust system for the following conditions:
Leaks
Damage
Loose hardware
Missing hardware
Ensure that the HO2S 1 and the HO2S 2 are secure, and ensure that the pigtails and the wiring are not damaged or contacting the exhaust.
Did you find and correct the condition?
Go to Step 5
Go to Step 4

4
Replace the catalytic converter. Refer to Catalytic Converter Replacement in Engine Exhaust.

Is the action complete?
Go to Step 5
--

5
Use a scan tool in order to clear the DTCs.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC run and pass?
Go to Step 6
Go to Step 2

6
With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?
Go to Diagnostic Trouble Code (DTC) List
System OK

If the problem didnt switch sides, either the O2 sensor connector female pins are defective, one or more of the wires is damaged or the CAT is bad.

If it were me, I would DATA LOG the engine and monitor the O2 sensors. That will easy eliminate or prove the sensor good or bad. Compare both rear sensors.

I have an ACTRON CP9180 scanner and it has LIVE SENSOR Monitoting capabilities. You can also use EFI Live and HP Tunes or find someone who has it.

Bill

 

Its pretty self explanatory. The cat is bad. Replace the front pipe.

 

Thanks for the info, Bill, it was indeed the cat.

 

If I were to always rely on the computer, I would spin my wheels much of the time.

You see, I have had computer reported problems in the past, and every single one of them was NOT as the computer indicated. Up until now, they've ALL been the result of faulty connections, and I live in Northern California, where we have no salt on the roads, and very little rain. Hence, there reason for my posts.

THIS time, the computer report was actually correct. There were no bad connections, no wiring issues, and no bad sensors. It was a bad cat, even though it sniffed clean. I guess the computer did a good job of changing fuel ratios to enable it to burn clean, even though the cat was bad.