как проверить катализатор своими силами?

Нейтрализатор может засоряться, попробуйте снять его и погазовать. Если двигатель перестанет тупить как раньше, то проблема в нём

1. Disconnect the oxygen sensor connector and connect
the special tool (test harness) to the connector on the
oxygen sensor side.
13
2. Make sure that there is continuity [7–40 Ω at 20_C] be- Index
tween terminal 3 and terminal 4 on the heated oxygen
sensor connector.
3. If there is no continuity, replace the heated oxygen sensor. 13A
4. Warm up the engine until engine coolant is 80_C or higher.
5. Use the jumper wires to connect terminal 3 of the heated BASE
oxygen sensor connector to the battery (+) terminal and
terminal 4 to the battery (–) terminal.
Caution
Be very careful when connecting the jumper wires;
incorrect connection can damage the heated oxygen
sensor.
6. Connect a digital voltage meter between terminal 1 and
terminal 2.
7. While repeatedly racing the engine, measure the heated
oxygen sensor output voltage.
Standard value:
Engine
When
racing
engine
Heated oxygen sen-
sor output voltage
0.6–1.0V
Remarks
If you make the air/
fuel ratio rich by
racing the engine
repeatedly, a normal
heated oxygen
sensor will output a
voltage of 0.6–1.0V.

чек!

загорится чек - диагностика покажет "низкая эффективность катализатора" или что-то вроде этого

Подуть в него.