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What is the effect of fouled or failing catalytic converters?

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Mainly increased emissions and a failure at the smog test. There isn't much effect on drivability.

Posted on Dec 09, 2016


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Why does my 98 honda civic fail NO?

run the fault codes to check for sensor problems that is causing this result.

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Have foul Odor in 2000 330i when driving could it be fuel mixture

your catalytic converter is likely dying. Doesn't affect the car but you will probably fail your next emisssions inspection.

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All 4 O2 Sensors failed at the same time

Check the relays and fuses for the H.E.G.O (heated oxygen sensors) for power and function.

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Catalytic converter problems

You will get a fault code to that effect . Also if you can get underneath the car and hit the converter with the heel of your hand and it rattles then that is also a good indicator that it has failed.

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Hi, I have a 96 Jeep Cherokee with straight 6 cyclinder engine.The check engine lights on and Itook get to be put on a machine and the codes readed P0132,P0135,P0300,P0301,and P0420. Could you tell me

p132+ an O2 sensor reading is high bank1,sensor1, p135=O2 Heater circuit is bad, bank1,sensor1.

P300= Random misfires, p301 misfire cylinder1.p302 misfire cylinder2

p420 Bank1 Catalytic converter efficiency failing

What this means is that the Bank1 O2 sensor is either bad or the wiring to it is defective. Check for heat burnthrough on wires. The misfires started randomly and now pinpoint to cylinders 1 and 2.

The Catalytic converter failing because the misfires are clogging it. This can self correct once the cylinders stop misfiring.

Which messed up first is where you start solving this. Replace the O2 sensor, it is fouled out on Bank1. The heater circuit(p135) just makes it work faster and has little effect once you are underway. But high resistence in the O2(p132) means it is coated and ineffective.

There is a problem with firing #1 and #2 sparkplug. Probably the cause for the Catalytic converter plugging. A cracked coil, plug wires, sparkplugs are some causes as well as dirty fuel injectors on those 2 cylinders.

It is a cause and effect situation where 1 part fails and damages another. You need to fix the source of the problem or you will repeat th damage.

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How do you know if your cat converter is going bad? Can you test for it?

There are two ways a converter can fail:
  • It can become clogged.
  • It can become poisoned.
There really is no "inspection port" for the consumer or mechanic to see an actual clog in a converter. Often, the only way to tell if a catalytic converter is malfunctioning (plugged) is to remove it and check the change in engine performance. When a clogged converter is suspected, some mechanics temporarily remove the O2 sensor from the exhaust pipe ahead of the catalytic converter and look for a change in performance.
A catalytic converter relies on receiving the proper mix of exhaust gases at the proper temperature. Any additives or malfunctions that cause the mixture or the temperature of the exhaust gases to change reduce the effectiveness and life of the catalytic converter. Leaded gasoline and the over-use of certain fuel additives can shorten the life of a catalytic converter.
A catalytic converter can also fail because of:
  • Bad exhaust valves on the engine
  • Fouled plugs causing unburned fuel to overheat the converter
­Sometimes you can tell that a converter is clogged because you don't go any faster when you push the gas pedal. Also, there usually is a noticeable drop in gas mileage associated with a clogged catalytic converter. A partially clogged converter often acts like an engine governor, limiting the actual RPMs to a fast idle. A totally clogged converter causes the engine to quit after a few minutes because of all the increased exhaust back pressure.
The catalytic converter, like the rest of the emissions system, typically has a warranty length that exceeds the term of the warranty for the rest of a typical U.S. automobile.
Here is a safety reminder: Do not park your car over tall grass or piles of dry leaves. Your car's perfectly running catalytic converter gets very hot -- enough to start fires! You can keep it running well by keeping the ignition system in top shape, to prevent any unburnt fuel from entering the catalytic converter.

Dec 11, 2010 | 1989 Dodge Dakota 2WD

1 Answer

Trouble code po430 what does this mean? also car sputters or hesitates when drivng runs smooth at idle ?

This code means the Catalytic converter on bank 2 is not working efficiently. If your car is acting up with hesitation the Catalytic may be getting fouled by the way the engine is running. There may be another Code to read for the problem that caused the Catalytic converter to foul.

You have between 25 and 35 Startups before a Code is erased. Consider the Code 430 as the last Code recorded and the other Codes were beyond the 25 to 35 Startup limit.

You have several choices. (Autozone and Oreillys give free scans) There are fuel additives which claim to clean the fuel system and Catalytic converters. You can have the car put on a better machine at a Dealer to find the cause of the hesitation. BUT tell them you want the type of test for cylinder balance and timing issues, not just Code numbers.

Once you restore the engine to Specs, the Catalytic converter may clean itself over time.

Nov 14, 2010 | 2000 Mercury Grand Marquis

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My Dodge Dakota won't go above 30 miles an hour and acts like it is going to stop running when the gas tank gets below half full

may have a weak fuel pump, same happened on my dakota, was the fuel pump ,also change fuel filter same time

Dec 06, 2009 | 1995 Dodge Dakota

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How do I fix the PO421 code? I own a 1996 Ford Probe that hasd failed the e-check because of the PO421 code. What do I need to do to solve this issue?

the trouble code means that the oxygen sensor is reading that your catalytic converter is no longer operating properly. Either the oxygen sensor(s) is faulty and is giving an incorrect reading or the catalytic converter is faulty. You should have a flow test performed on the cataytic converter to ensure it is performing properly. You can also check your oxygen sensor(s) before replacing them

Sep 30, 2009 | 2003 Mitsubishi Lancer

1 Answer

P 0421 code when took emissions test

Either your O2 Sensor has failed, your catalytic converter has failed, or one of your spark plugs is fouled up

Sep 28, 2009 | 2003 Mitsubishi Diamante

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