The vehicle’s exhaust gas purification system is relatively complex, and the catalyst is one of its elements. It is also called a catalytic converter. Its main task is to turn harmful substances emitted into the atmosphere into less harmful, and error P0420 indicates that this exhaust gas purification element does not work well or does not work at all. In some cars, two neutralizers are used at once. In this case, the error code may be P430. If such an error occurs, then first of all this indicates that the catalyst life has come to an end. Of course, there is a chance that the error arose because of the poor quality of gasoline (and this is the case), but most often the problem is precisely in the "death" of the catalyst. Well, or in low work efficiency.
Why is error P0420 formed?
The car’s “brains” during operation (control) compare the signals from two sensors during a certain time interval, calculate the duration of voltage signals, and if it does not fit into a given threshold, the system considers this to be a malfunction of the converter. It is believed that the difference between the amplitudes of the oxygen sensors (front and rear) should not be more than 0.7 times per minute. However, the Check engine light does not light up immediately, but within 100 seconds. In this case, the engine load should be from 21 to 63% at a crankshaft rotation speed of 1720-2800 rpm. Also, the temperature of the catalyst should be more than 500 degrees.
If the catalyst is worn, then the reading of the rear oxygen sensor will gradually approach the reading of the front. The main purpose of the catalyst is the oxidation of carbon monoxide and the neutralization of CO 2 emissions into the environment. Starting with the Euro-3 standard, two sensors monitor this process, between which signals are constantly compared in order to register the convergence of readings between them. Therefore, sooner or later, in any case, error P0420 occurs: on Ford Focus 2, Nissan, Chevrolet, Honda, Toyota and other cars that were released after 1996 and have two lambda probes (2 sensors).
So, the main cause of P0420 error is the detection of unburned fuel and oxygen residues in the exhaust gases. And yes, this is only a matter of time, because the catalyst has a limited life. And this service life largely depends on the quality of gasoline that the owner of the car runs.
Symptoms of Error P0420. How does a car behave?
Depending on how the catalyst "dies" (clogged or begins to destroy), the car can behave differently. But the first signal is that the Check engine light on the instrument panel lights up. Some cars even have a special lamp for overheating the catalyst, so even the error does not have to be diagnosed. This means that the exhaust gases no longer meet Euro 3-5 standards.
Basically, when error code P0420 appears, in parallel with it is observed:
- Higher fuel consumption. If a car usually consumes 8 liters per 100 km, then with a non-working catalyst, consumption can increase to 9-10 liters per 100 km.
- The dynamics of the car is reduced.
- The smell of exhaust gases changes and becomes more pronounced.
- There is rattling from the side of the catalyst.
- Unstable idling (jumps in revolutions) can be observed.
If at least a few of the above signs are observed, then this indicates a problem with the catalyst. Therefore, vehicle diagnostics are required.
Causes of P0420 Engine Error
During normal engine operation, the catalyst has a working life of 200-250 thousand kilometers. However, when refueling with a high lead content, the valve will "die" much faster. Also, due to possible malfunctions of the ignition and gas distribution, compression may be disrupted. As a result, there will be misfires, which also accelerates the destruction of the catalytic converter and entails a P0420 error on the Ford Focus 2 and other cars.
Therefore, low-quality gasoline, which motorists regularly refuel their cars with, is the first cause of catalyst damage. It can break down after 80 thousand kilometers, although initially it is calculated on 200-250 thousand provided that the machine runs on normal gasoline.
Causes of Error P0420:
- The use of leaded gasoline.
- Failure of the oxygen sensor S2.
- Short circuit in the "lower" oxygen sensor system.
- Damage in the system of another element: exhaust manifold, pipe, muffler, etc.).
- Catalyst damage.
- Continuous operation of ICE with misfire.
- High fuel pressure.
It follows that there can be 7 reasons for the P0420 error on Ford Focus 3 and other cars where lambda probes are used in the exhaust gas purification system. However, more often than not, everything is much simpler, and drivers just need to refuel with good gasoline or put the oxygen sensor on the snag. In rare cases, lambda contacts simply "sit" poorly, because of which the system does not see them and displays an error.
But in order to correctly and determine the problem that caused this error, you need to diagnose the car. In certain cases, it is necessary to check the exhaust system, manifold or oxygen sensor for leaks. Leaks and leaks could well affect the operation of the sensors, which was expected to cause error P0420. But most often the catalyst is to blame.
Troubleshooting Tips
Before you run into a car service, try to find out the reason yourself. To do this, you need to carry out a few simple checks. First, try to remember at which gas station the last time you refuel and whether the correct fuel was poured. If previously you always poured A98 gasoline, and for the last time you decided to test the A92, it is quite logical that the system showed error P0420. In this case, just roll the remains of A92 and refuel this time with A98. For many car owners, after a change in gasoline, the error disappears.
Next, check the rear oxygen sensor connector. If he moved away a little, then this could well have caused an error. If this is all right, then you will have to connect a computer to remove errors and data from the control unit.
Catalyst Test
To verify the correctness and efficiency of the catalyst, compare the voltage graphs between the two oxygen sensors. The computer will clearly see a decrease in output voltage during lean mixture and an increase during enrichment. If the voltage of the oxygen sensor in the region of 900 millivolts, then this indicates the enrichment of the mixture, 100 millivolts indicates the depletion of the mixture.
Debugg
Many car owners, out of ignorance of the cause of the error, try to eliminate it by replacing the sensors or cleaning the damper. But this does not help, because the reason lies elsewhere.
First, you need to try swapping lambda probes. They are the same in type and can replace each other. If the second oxygen sensor was faulty, then we will get another error (as an option, P0134). Such diagnostics are simple and effective only if the second sensor fails. If the problem is not with the sensors at all, then the error will not disappear.
Secondly (this has already been said), you need to try to refuel with better gasoline. If the reason was fuel, then after 2-3 days the error will disappear.
The third step in solving the problem (if all else fails) is to check the catalyst. We need to check its bandwidth. Its destruction could occur due to improper operation of other engine systems. And if this element was overheated, then a similar error could well have arisen.
Solving the problem of low catalyst efficiency
Often the problem of a catalyst with poor efficiency is solved by flashing the ECM. It simply puts another software, where another toxicity standard is laid (for example, EURO2). The system still compares the value for two sensors, but now the difference in the parameters will correspond to the toxicity of EURO2. What can this be achieved? At a minimum, the error on the dashboard will disappear, but nothing more.
Catalyst replacement
The most expensive option is to replace the old catalyst with a new and original one. However, this is an expensive procedure due to the high cost of the device itself. The price can reach 40 thousand rubles.
A cheaper option is to use a universal catalyst, which has lower operating efficiency compared to the original (the thing is in the material: the original catalyst is ceramic, and the universal one is made of metal). Also, its resource is only 30-50 thousand kilometers, and not all cars accept it well. But then no software changes are needed in the system. And another option: in the disassembly, you can find the original catalyst, although it was second-hand. It will not be known what his mileage and how soon he will fail.
Installing a flame arrester
If toxicity standards do not bother you at all, then a cheap and concise option is to install a flame arrestor. For this, a catalyst can is cut out and a blende of a second lambda is installed. This is called hardware dummy, but there is software. We are talking about flashing the system and translating it into a reduced toxicity rate. It is worth noting that such a solution to the problem, although it involves more severe air pollution on the street, but greatly increases engine power. After all, all these toxicity standards and environmental standards cut down on engine capabilities.
Removing the catalyst from the system
Alternatively, the catalyst can be completely removed from the exhaust system and a two-channel emulator can be installed, with which you can adjust the signal speed, response time.
It may also be that during the diagnostic process it turns out that the throughput of the catalyst is normal (about 0.21 kg / cm 2 at 2000 rpm). This is quite possible, because the error works even if the catalyst operates at 70% of its capacity. In this case, you can put a special spacer under the lambda probe. This is a very cheap solution, but it cannot be said that it is a panacea.
