A clogged catalyst is a common malfunction in high mileage vehicles. Over time, a system breaks down that serves to reduce exhaust emissions. Usually the first signs of this condition are observed after 150 or 200 thousand km. But sometimes it can occur earlier if the engine is not properly operated or a manufacturing defect takes place. Today we’ll talk about the symptoms of a clogged catalyst. How to understand that catalyst is clogged and fix the problem?

Signs of a clogged catalyst

Classic symptoms of a malfunction are a decrease in dynamics of a car and a noticeable cut in engine power. As a result, the level of maximum speed decreases; the car accelerates sluggishly during overtaking or when starting at a traffic light. Additional signs which shows that catalyst is clogged or not:

 

  1. Motor starts hard on both hot and cold temperature, a strange sound appears.

  2. Power unit may fail completely if the assembly is too clogged.

  3. Exhaust fumes start to smell unusually, this smell resembles a rotten egg (in fact, it is hydrogen sulfide).

 

One way to identify a clogged catalyst is by checking the CheckEngine indicator light on the car dashboard. Often in such a situation, it lights up. Same symptoms are observed on a diesel engine.

 

In case of damage to wires that transmit the signal from sensors, or unexpected destruction of active substance, warning lamp lights up. Sensors are mounted after the outlet and before the inlet pipe, they serve to control the oxygen concentration. When catalyst clogging occurs gradually, the bulb does not let you know that a system problem has occurred.

 

The reason for this may be poor ventilation of cylinders. When it weakens, the power unit cannot capture enough air the increased back pressure of catalyst interferes. The exhaust partially remains inside cylinders and does not allow the air-fuel mixture to properly fill the combustion chamber. For this reason, dynamics worsens, power decreases. The main thing to know is if the catalyst is clogged, how the machine behaves and why it is dangerous.

 

How to identify a clogged catalyst?

For the following reasons, catalyst is usually clogged:

 

  1. There are certain defects in engine or exhaust system. For example, the increased oil content in exhaust and its increased consumption.

  2. Low-quality fuel that does not completely burn out in cylinders and burns out already in exhaust manifold. Catalyst may melt or simply overheat.

  3. Too small throughput cells of a catalyst. They quickly clog, and even small droplets stick because of heat.

  4. Poor quality pavement affects catalyst clogging. From constant mechanical shocks about bumps, speed bumps, mounds suffer from its internal components. And if at least one cell is damaged, then its particles can clog remaining cells.

 

Implications for an engine

Do not neglect tips to check the catalyst for clogging, since consequences of driving with such a node can be most severe for a car. A defective element provokes following problems:

 

  • Increased operating costs of gasoline due to increased resistance of the exhaust tract.

  • Exhaust fumes contain a lot more harmful substances.

  • Engine power drops significantly, and, consequently, comfort of a trip in a car.

  • The main thing that threatens a long ride with a clogged catalyst is a complete breakdown of gasoline engine. At one point, it will stall right in the process of movement, or it won’t start at all.

It is especially dangerous for motor if the internal filling of a catalyst is destroyed. In this case, solid particles are formed that penetrate the cylinder and become clogged between the piston and the inner surface. Because of them, damage is formed on the mirror, and they can be removed only by grinding.



 

How to check the catalyst for clogging without removing it?

Three most common methods to find out that a catalyst is clogged:

 

  1. Complete dismantling of working unit and its external inspection for signs of clogging. Removing the catalyst is sometimes problematic because it tightly sticks. In this case, the specialist uses a grinder. Also, some cars have such complicated designs of exhaust systems that it is generally impossible to remove catalyst or it takes several days.

  2. Measurement of pressure in exhaust system. To measure it, it is necessary to install the pressure gauge in place of the 1st oxygen sensor, and then take readings at different engine operating modes. The pressure is considered correct at level of 0.3 kgf / cm², at 2.5 thousand rpm. It is often difficult to remove sensors.

  3. Back pressure measurement with a special tester. A pressure sensor is mounted in a place of the spark plug in the engine cylinder, after which an oscillogram is analyzed at increased speeds.

The replacement or repair of the catalyst is definitely required in a situation where the pressure in exhaust system is more than 200 kPa (almost 2 kgf / cm²).

 

What is included in a repair of a catalyst?

Try to clean the contents of catalyst from particulate matter and carbon deposits. This method is effective only in early stages of pollution, when the car does not show any malfunctions.

Remove the filler from the housing, then install emulators and flame arresters to replace oxygen sensors. Having done this, you can forget about problems with the catalyst, but this is a serious intervention in design of the exhaust system. Fines are possible if representatives of law reveal increased atmospheric pollution using a special gas analyzer. In addition, catalyst removal interferes with error detection by sensors. As a result, they will always give the same readings.

Consider full replacement of the old catalyst with a new one. The right way is expensive enough, because purchase and installation of a new catalyst will cost from 100 to 1200 USD, based on the brand of car.