To determine whether the three-way catalyst is blocked or damaged, the following methods can be used for detection:

1、 Oxygen sensor voltage detection

Method: Compare the oxygen sensor voltage before and after the three-way catalyst.

Judgment criteria: If the two voltages are the same, it may indicate that the three-way catalyst has been damaged, which may be caused by blockage or engine misfire.

2、 Exhaust pipe airflow detection

Method: Stretch your hand near the exhaust pipe and feel if there is any airflow passing through.

Judgment criteria: If there is no obvious gas flow, it may indicate that the three-way catalyst is blocked.

3、 Air filter test

Method: After removing the air filter, perform rapid acceleration and throttle operation in place.

Judgment criteria: If black smoke is observed emitted from the air filter, it usually indicates a malfunction or blockage of the three-way catalyst.

4、 Temperature sensing detection

Method: Determine by sensing the temperature difference before and after the three-way catalyst.

Judgment criteria: If the temperature difference before and after the three-way catalyst is very small or large (specific manifestations may vary depending on the vehicle model and operating conditions, but generally speaking, a large temperature difference is more likely to indicate blockage), it may indicate that the function of the three-way catalyst is damaged or blocked.

5、 Vehicle speed and acceleration performance inspection

Method: During the test drive, observe whether the vehicle can reach the maximum speed and whether the acceleration performance is good.

Judgment criteria: If the maximum speed cannot be reached or the acceleration performance is poor, it may be due to blockage of the three-way catalyst.

6、 Exhaust back pressure measurement method

Method: Use professional equipment to measure the exhaust back pressure before and after the three-way catalyst.

Judgment criteria: The exhaust back pressure before the three-way catalytic converter of a normal vehicle is relatively small, generally around 0.004MPa at idle and not exceeding 0.01MPa at 3000 rpm. If the exhaust back pressure rises to 0.025MPa or even higher at 3000 rpm, it may indicate a slight blockage, and the higher the pressure, the more severe the blockage.

7、 Dismantling inspection method

Method: Disassemble the three-way catalyst directly for inspection.

Judgment criteria: By observing the internal condition of the three-way catalyst, it is possible to intuitively determine whether there is blockage, damage, or other forms of damage.

It should be noted that the above methods are not absolutely accurate, as the performance of three-way catalytic converters may vary depending on different vehicle models and operating conditions. Therefore, when making judgments, it is recommended to consider multiple methods comprehensively. At the same time, if there is suspicion of a problem with the three-way catalytic converter, it should be promptly inspected and repaired at a professional car repair shop to avoid further deterioration of the problem and more serious consequences.