Home TroubleshootingExhaust Catalytic Converter Not Ready: Will I Pass A Smog Test?

Catalytic Converter Not Ready: Will I Pass A Smog Test?

by Kelvin Yates

Modern cars have different systems that regulate and monitor performance. They check on emission, the volume of gas injected into the engine, the volume of fluid needed for shifting, etc. One of the car’s emission components that are monitored and regulated is the catalytic converter. This is a very essential component that ensures your car’s emission is environmentally friendly. Have you ever taken your car for an emission test and you find a “catalytic converter not ready” test output?

As mentioned earlier, a car can carry out self-regulation and analysis. This helps the car identify any components that are malfunctioning besides checking on fuel consumption, emission, and fluid use. Modern cars comprise two types of monitors; continuous monitors and non-continuous monitors.

The difference between the two types of monitors is that continuous monitors can function anytime provided that the engine is up and running. While non-continuous monitors can only function under given conditions such as; acceleration, speeding, ambient, fuel levels, fluid levels, and during the need to carry out internal automatic self-tests on your car.

Contents of this article entail;

Emissions And The State Laws

One of the non-continuous monitors is the catalytic converter. The major role of the catalytic converter in your car is to monitor the ability of your car to reduce the emission of toxic/harmful gasses into the atmosphere. This is because different states in the USA have got their state laws regarding emission.

All vehicles operating within those states with strict emission regulations must go through periodic smog tests before they can be allowed to continue to be on the road. What if you go for this test and you find a “catalytic converter not ready” message? Then you are kept to carry out continuous weekly or daily smog tests until it gets ready. This can be so annoying. How do you get it ready? Keep reading since we shall give the tips and tricks.

Purpose Of Catalytic Converter

Before introducing catalytic converters, vehicles used to emit enormous volumes of toxic fumes to the atmosphere. Fortunately, things took a twist in the 1970s when environmental conservation took center stage. There started the push to restrict the emission of toxic fumes into the atmosphere.

Legislations and laws were eventually put in place to regulate the rampant emission of hydrocarbons into the atmosphere to minimize pollution. It’s these laws that forced auto manufacturers to reduce the toxicity of fumes their cars could emit.

Then came the introduction of the catalytic converter to help in neutralizing the toxic fumes. The catalytic converter is an important component in vehicles. Its major function is to neutralize harmful emissions from burning gasoline in a car’s engine.

The catalytic converter is a metal canister that forms part of the exhaust system. It uses chemical catalysts that remove pollution elements from the engine’s exhaust gasses. This makes the gasses harmless to organic life.

How The Catalytic Converter Works

The catalytic converter neutralizes harmful gasses including nitric oxide, carbon monoxide, and excess hydrocarbon fuel which causes smog and are harmful to organic life. With the presence of the catalytic converter, the gasses are supposed to pass through the ceramic lattice-like honeycomb of the converter coated with copper, platinum, and palladium.

During this process, the toxic gasses are broken down into oxygen, carbon dioxide, and water. This helps reduce harmful emissions by over 90%.

When the catalytic converter malfunctions, the harmful gasses cannot be neutralized before being released into the atmosphere. This increases the rate of harmful emissions resulting in pollution and global warming.

The catalytic converter is a vehicle component that lasts for the car’s lifespan. But different factors can lead to its failure to perform its crucial function efficiently. These factors may include; wear and tear over time, high mileage on the road, or stones and debris that keep knocking it.

If you live in a state with strict emission laws, it’s obvious that if you have a malfunctioning catalytic converter, you won’t pass the smog test. Keep your car off the road until you have your converter repaired or replaced. Else you risk your car being impounded and heavy fines slapped on you.

Why The Catalytic Converter Malfunctions

As earlier stated, a catalytic converter should last for the vehicle’s lifespan. But just like any other vehicle component, it can experience wear and tear. This can eventually lead to premature breakdown. Here are some conditions that may drastically lower the efficacy of your catalytic converter.

High Mileage

As the car continues to be used, it keeps on covering more mileage. As this happens, the chemical lattice found in the catalytic converter that is responsible for neutralizing hydrocarbons eventually gets weak or depleted. This layer can only be good and effective up to a specified mileage. Anywhere past that it gets depleted and becomes ineffective.

Knocks And Impact

Stones and debris on the road can damage the catalytic converter. As the vehicle moves, the stones that are displaced by the moving wheels can sometimes hit the catalytic converter with high impact. This can eventually break the converter and make it leak.

A leaking converter will not pass the smog test because it’s ineffective.

Unburned Fuel In The Exhaust

This normally happens when the spark plugs are worn out or the engine valves are damaged. This allows unburned fuel into the exhaust system. These unburned fuels eventually burn inside the catalytic converter, causing damage to the damage of the chemical lattice and other purification substances in the catalytic chamber.

Electrical Faults

Electrical faults usually occur when the spark plugs cannot get enough power. When this happens, the unburned fuel once again finds its way into the exhaust system and the catalytic converter. They will burn in the catalytic chamber and damage the inner components of the catalytic converter.

Fuel Or Oil Leaks

When a car’s piston rings are worn out or in case there is a jumped timing chain, unburned fuel finds its way into the converter and ends up damaging the components of your catalytic converter. This drastically lowers the efficacy of your converter.

Oil And Coolant Leaks

The prime culprits causing the leakage of oil and coolants are usually the head gasket or the intake manifolds. When these two have some leakages, the oils and the coolants find their way into the catalytic converter.

This is usually enough reason for the check engine lights to be triggered.

The Symptoms of Failure

A malfunctioning catalytic converter will start showing certain signs that a keen driver can easily identify. When you see your vehicle exhibits any of these symptoms below, it would be good to have it checked by a professional mechanic to help fix the problem.

Engine Misfiring

The catalytic converter can exhibit signs of failure when the engine misfires, or if there’s an excessively rich oil and fuel mixture that can ignite in the convertor, causing damage to the components on the ceramic lattice.

Poor Acceleration

One of the most common signs that your car’s convertor is failing because of a blockage, is a loss of power when speeding up, particularly when going up a hill. One simple test you can perform is asking a friend to hold the engine revs at around 1800 to 2000 rpm whilst you feel the airflow from the exhaust. Hot gasses show problems with the converter.

Loss of Engine Performance

When the catalytic converter becomes clogged up and cannot process exhaust gasses, it becomes harder for the engine to flush out the waste products of combustion.

This in effect strangles the engine of oxygen and power, causing the car to shake with sudden bursts of pressure stalling the engine.

Poor Exhaust System Performance

Check the performance of your exhaust. It will seriously drop off if there’re problems with the fuel system which could be caused by issues with the catalytic convertor.

Rattling Sounds

If you are hearing rattling noises coming from the rear of the car, then this could be because of the degradation and break-up of the honeycomb-like ceramic lattice within the catalytic convertor. You’ll notice a slight rattling when the car starts, which then worsens.

Sulphur-Like Odours

One of the strongest smelling gasses that a catalytic convertor absorbs is hydrogen sulfide, which is a sewer gas with a distinct rotten egg-like aroma. If you can smell this unamicable odor coming from the back of your car, then the chances are that the effectiveness of this part has dropped to an unacceptable level.

Bad Fuel Economy

One of the easiest signs to spot from behind the wheel of the car is poor fuel economy. As a rule of thumb if your open road miles per gallon drops below 10% of the normal value then it’s likely there is a fault in the catalytic convertor. It’s worth equally checking the fuel pump and the fuel filter too as these could also cause the problem.

Check Engine Light

A damaged or failing catalytic convertor will often cause the check engine light to illuminate. Many of these modern systems work using an air-to-fuel ratio tester and an oxygen sensor that monitors exhaust fumes. If the system is not working correctly, this will trigger the warning light.

However, as there are many issues with the engine that can activate this light, it is best to have your car scanned to find out the source of the issue.

Fuel Vapours

If your vehicle has a carburetor, then there’s a simple test you can perform to check the catalytic converter is functioning correctly.

Simply remove the air cleaner and get a friend to hold a light source near the intake, which will illuminate a cloud of fuel vapor if there is a blockage in the convertor. This is a great little test as it identifies the convertor as the problem with your system.

As the catalytic converter breaks down, its effectiveness also diminishes. Harmful gasses that were once stopped by the part will now get out into the atmosphere. Whilst it is tough to notice this yourself, an emissions test will confirm any suspicions.

Take your car to a professional and have them inspect the system. They’ll give you a full report and let you know if you need a replacement catalytic converter. Make sure you’re also ware of how much for catalytic converter.

Catalytic Converter Not Ready

Living in any of the states with strict emission laws will compel you to take your car for periodic smog tests. Imagine driving your car to the emission test station to get it tested. Then suddenly it’s rejected because the smog test output shows “not ready”. Then you are left wondering what exactly this means.

“Not ready” basically means the Onboard Diagnostic System OBD II has not completed all of its self-test monitors that check on the performance of your emissions control system.

Depending on the model of your car, year of manufacture, and the make, there may be several OBD monitors that have to be completed first. A single or multiple “not ready” outputs can make your car cannot pass the emission inspection.

To pass an OBD II plugin emissions test, all of your car’s OBD monitors must have run and successfully completed with no faults. This tells the emissions to test computer that your car is performing within the emissions limit for your year, make, and model.

This shows that your car has complied with the applicable emissions laws hence the car isn’t emitting harmful gasses to the atmosphere.

The OBD system is always constantly monitoring some operations within your car every time the engine is running. Some of these operations can only be monitored under certain driving conditions.

Some checks can be described as continuous and are always ongoing anytime provided the engine is running. The continuous checks include;

Misfiring Monitoring

This helps to monitor and detect ignition and fuel-related misfires that may cause emissions to increase and damage the catalytic converter.

Fuel System Monitoring

Helps in detecting changes in fuel mixtures that may contribute to an increase in emissions.

Comprehensive Component Monitoring

This helps in detecting any major faults in the engine sensors that may contribute to an increase in emissions.

Catalyst Efficiency Monitor Not Ready

The function of the catalyst efficiency monitor is to verify that the catalytic converter is operating at an optimal efficacy to help keep the exhaust emissions at the recommended limit as stipulated by law. The role of the monitor is to compare the signals from the upstream and downstream sensors to monitor how the catalytic converter operates.

If by any chance the catalyst drops below the stipulated threshold, the converter automatically sets a fault code P0420 and or code P0430 and the check engine light is triggered to illuminate.

If the converter conversion efficacy goes below 80% for any pollutant be its carbon monoxide, hydrocarbons, or oxides of nitrogen, the vehicle may not comply with the emissions law. It will emit toxic gasses causing the codes to set.

In modern car models, the Low Emission Vehicles (LEV) and the Ultra-Low Emission Vehicles (ULEV) have a less margin for error. The catalyst monitor may set the code if the efficacy of the catalytic converter just drops below 90%.

Additionally, the catalyst monitor may require certain driving conditions before it can run. This will depend on the model of the car. The HEGO (oxygen sensor) has to be completed first.

This can be followed by driving at highway speed of 55 MPH for at least five minutes under light load, no conflicts with other monitors that haven’t run i.e. the EVAP and EGR monitors that have to complete before the catalytic monitor can run and no-fault code could affect the accuracy of the test.

Some cars have a specific drive cycle that must be followed to enable the catalyst monitor to run. Sometimes, you may be forced to complete the prescribed drive cycle many times before the catalyst monitor can run.

Catalyst Monitor Drive Cycles

Here are some of the sample drive cycles for the catalyst monitor to run and help diagnose catalytic converter, not ready output.

Ford: the catalytic monitor will only run when the HEGO oxygen sensor has run and completed with no faults identified. Drive your car in the stop-and-go traffic conditions at five different cruise speeds ranging from 25 to 45 MPH for 10 minutes.

General Motors: the catalyst monitor will run after driving at 55 MPH for five minutes. But this may take up to five drive cycles at this speed before the monitor can run.

Chrysler: the catalyst monitor will not run until;

  • The check engine light is off
  • No-fault codes are present
  • The fuel level is between 15 and 85 percent full
  • The coolant temperature is above 70 degrees F

When all the above conditions have been achieved then, the engine must have run for at least 90 seconds and the engine speed must be between 1,350 and 1,900 RPM. You can now idle the vehicle for five minutes for it to reach closed-loop operation. You can then drive at a steady speed of 30 to 45 MPH for two minutes.

Toyota: the Toyotas catalyst monitor will run after driving the vehicle at a speed of 40 to 55 MPH for seven minutes, followed by driving at 3,500 to 4,500 RPM for another seven minutes.

Common Causes of Catalytic Converter Not Ready Rejection For Emissions Testing

All the applicable OBD monitors for your year, make and model of the vehicle must have been run and completed to be accepted and pass an OBD plug-in emission test. Any of the following may cause your vehicle to not be ready:

Disconnecting The Battery For Any Reason

This erases the memory in the PCM, including stored fault codes and previous OBD monitor test results. It’s like resetting the clock back to zero. It may take several days or even weeks of driving before all the monitors will run, allowing your vehicle to be tested.

Erasing Stored Codes With A Scan Tool

This also resets all the monitors back to zero, so allow plenty of time for the monitors to run before driving back to the emissions test facility. If any of the erased fault codes reappear, it may prevent one or more of the monitors from completing.

Disconnecting Sensors

This will prevent the monitors from running and will probably set one or more fault codes.

Removing The Catalytic Converter

This is emissions tampering and is illegal for street-driven vehicles.

Installing A Performance Tune With An Aftermarket Tuner Tool

This changes the stock programming and calibration of the engine computer. Such changes are often made to increase power, change shift points, recalibrate the speedometer for different gear ratios or wheel sizes, change rev limiters, and so on.

Tuning modifications may also be made so the engine will run properly with aftermarket performance accessories such as a cold air intake, exhaust headers, low restriction converters or mufflers, performance camshafts, and intake manifolds.

But changing the programming may prevent some monitors from running. Some of these programs disable the downstream O2 sensors, which will prevent the catalyst monitor from running. The fix is to return the programming to stock which may also require temporarily removing some of the aftermarket performance parts and tools.

Cheating The System By Installing A PCM Simulator

This is meant to fool the emissions test station, a trick some performance enthusiasts use on highly modified vehicles to “pass” emissions. If you get caught, it will cause rejection and you will probably have to undo some or all of the performance modifications you have made to your vehicle to pass the test.

Diagnosing Catalytic Converter Not Ready

When you take your car for an emissions test, the output is always either “not ready” or “ready”. When the results of your test are indicated as “not ready” that means that your drive cycle has not run completely hence the catalytic monitor hasn’t tested the catalytic converter.

To make the output “ready” you will have to carry out some troubleshooting as stated in the steps below.

Ensure The Check Engine Light Is Off

Confirming if the check engine light is on is always the first step to take in this troubleshooting catalytic converter not ready problem. If by any chance the car has some active trouble codes, this may prevent the monitor from running completely.

Confirm The Car’s Coolant Temperature

This has to be done mainly because a drive cycle usually starts with a cold start. The temperature of the engine coolant should be below 50 degrees and 6 degrees of the air temperature. Having your car sit overnight can help you achieve this and help diagnose catalytic converter is not ready.

Idle The Engine For 2 Minutes

This would involve starting your car’s engine then letting it stay on the idle mode for approximately two and a half minutes. As you do this, ensure that the defroster and the AC compressor are on.

Drive The Car At A Constant Speed Of 55 MPH

At this juncture, switch your car’s rear defroster and the AC compressor off but keep the speed at 55 MPH for close to 3 minutes. The purge and the fuel monitor diagnostics will happen during this time.

Decelerate To A Speed Of 20 MPH

You can gradually let the speed of your car drop to 20 MPH. as this takes place don’t try touching or shifting the clutch or brakes.

Speed Up Once Again

Accelerate once more to a speed of 55 MPH at a ¾ throttle for about five minutes. This will trigger the catalyst monitor diagnostics to take place. In case the battery is detached or the catalyst is not ready, this might take five complete driving cycles to decide the condition of your catalyst.

Stop Your Car

Finally, you can slow down your car and allow it to be idle for approximately two minutes.

When the above steps are done carefully, it can aid in troubleshooting the catalyst monitor output “not ready”. Any time you take your car for a smog test and your car shows a catalyst monitor output of “not ready”, just follow the above steps to help troubleshoot the catalytic converter not ready problem.

Catalytic Converter Not Ready: Final Thoughts

You can drive indefinitely with a bad catalytic converter. But it is not good for the catalytic converter. You are also likely to encounter problems with the performance of your car. But this will not completely ruin your ride.

If over time your catalytic converter becomes plugged up with unburned fuel and by-products of combustion, then you may find yourself unable to drive at all.

Having your catalytic converter checked at the first sign of trouble can be a good idea. Remember, it is illegal to expel excess emissions from your car. Your car also risks being taken off the road if you fail the required emissions tests.

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