Lesson Plan Industry Sector

Lesson Plan Originally Created By: Richard Williams

Catalytic Converter (updated) by Richard Williams

Part of Unit: Engine Performance Fundamentals

Lesson Plan Overview / Details

This is an introductory lesson into the construction, operation and the diagnostic techniques used for the common automobile catalytic converter.

Lesson Time

120 Minutes
60 Minutes
180 Minutes
30 Minutes

Objectives and Goals

This lesson is designed to give the student a rudimentary knowledge of the construction, function and testing of the modern catalytic converter.

Activities in this Lesson


    As the students enter the classroom they will see a question written on the white board:

    What comes out of a car’s exhaust?

    I let them stew on this while I take roll and complete any other housekeeping tasks required. Then I ask the class for answers. Typically I’ll get the standard answer of CO, HC, NOx, CO2 and O2. If someone actually studied before class I may even get SO2. I agree with, and congratulate them on their correct answers.

    Then I ask them if we can simplify what they have come up with. After several minutes of attempts, I’ll suggest, "Whatever goes in the intake." After several seconds of looking at their confusion I’ll let them know it’s like when a group of guys and a group of girls go to a party. Now they’re still confused but much more interested. I’ll continue by saying things like girl #1 leaves the party with guy #4 and girl #2 & #3 leave with guys #5 & #6 and so on. I explain that everyone that went in is going to leave but not necessarily with the same persons they came with. They have been "re-arranged".

  • I now play a video clip that was downloaded from YouTube showing the construction, theory and operation of the catalytic converter

    Resources and Materials

    • Deconstruct Catalytic converter [ Watch Video ] [ Download Original Video ] This video is captured from the TV show "Deconstructid" and will show how a catalytic converter is made and works. (5min)
  • I now lecture from the classroom PowerPoint. I will also show selected parts under the video camera at the appropriate times. Students are encouraged to take notes and may use a copy of PPT notes pages downloaded from the school web site.

    Parts to be shown:

    -Cat substrate core

    -Cut away Converter

    -Melted portion of cat substrate

    Resources and Materials

  • Activity #4 Demo / Modeling

    Note: for this activity I have a video camera set up with large monitors for students to observe. The vehicle is also placed on an automotive lift for access.

    First I discuss the pre-checks needed before a cat test can be run, some of them being cooling system operation and basic acceptable engine function. I then demonstrate the "2 & 2" (2 minutes at 2500 rpm) method of warming up a vehicle's catalytic converter. I also caution the students that this is a minimum requirement and that a good catalytic converter may take up to five minutes to reach a "light off" temperature. I demonstrate the acceptable methods for properly testing the catalytic converter for efficiency, while wearing my safety glasses and explaining safety items to be aware of when working with catalytic converter systems.

    Methods to be used:

    1.  Tap test
    2.   Temperature difference
    3.  Engine off CO2/HC
    4.  Scan tool (OBD II vehicles)
    5.  Engine running intrusive test
    6.  Vacuum/back pressure
  • I will now ask the students to wear their safety glasses and ensure that they follow safe shop practices to complete several lab sheets using the methods and techniques learned in the demonstration.

    Resources and Materials

    • cat lab tap test.doc [ Download ] Lab Sheet
    • cat test 1.doc [ Download ] Lab Sheet
    • cat test 3.doc [ Download ] Lab Sheet
  • I now bring the students back into the classroom and bring up selected slides (the slides I bring up depends on my conclusions derived from questioning the students) and we discuss what we found.

    During this activity I try to get the students to answer their own questions. For example, one student may ask, "How do I know if the catalytic converter is warmed up enough?" I’ll ask the whole class if anyone can answer the question. If no one speaks, I review a slide that shows the warm up procedures and discuss how to confirm warm up of cat. If a student volunteers to answer I’ll listen to their explanation and try to find slides to support them and help them fill in the gaps.

  • Closure Closure

    Once in the classroom I’ll let the discussion dictate the questions I ask but they are typically similar to the questions I ask of the groups in the shop.

    Work sheets are reviewed for accuracy.

    Eventually they will be assessed by a written test.


Assessment Types:
Demonstrations, Interviews, Teacher-Made Test, Observations,

While the students are working, I’m visiting each group of students (2 to 3) questioning them, sometimes individually & sometimes as a group. I vary the questions such as:

1. What is this component?

2. Where is this component?

3. How does the component work?

4. What temperature should it be here?

Eventually there will be questions regarding this material on a written examination


  • Deconstruct Catalytic converter Deconstruct Catalytic converter [ Watch Video ] [ Download Original Video ] This video is captured from the TV show "Deconstructid" and will show how a catalytic converter is made and works. (5min)
  • Catalytic Converter classroom Power Point Catalytic Converter classroom Power Point [ Download ] This is the Power Point that I lecture from
  •  Catalytic Converter notes pages Catalytic Converter notes pages [ Download ] This is the Power Point I have for students' to use for note taking. It's best printed as a handout with three slides per page.