Catalytic Converters: Regulation, Replacement and Theft

Catalytic Converters: Regulation, Replacement and Theft

Catalytic converter replacement is easy – it is the ordering and associated paperwork that can be difficult.

You are not doing the customer or your shop any favors by either totally removing a catalytic converter or installing one that is not correct for the application. Catalytic converter replacement is easy – it is the ordering and associated paperwork that can be difficult. Doing your due diligence before and after the sale and service can help you to avoid fines and penalties from state and local regulators.


Everybody hates paperwork, but if you replace a converter, there are rules for both federal and state programs that you must follow:

• If the replacement is not required by a state or local program (due to an emissions issue), both the customer and installer must sign a statement explaining why the converter was replaced. Manufacturers either provide such a statement with the converter or have an example in their catalogs.

• If the replacement is required by a state or local program, the installer must keep a copy of the statement or order from the program representative.

• The invoice for replacement must include the customer’s name and complete address, the vehicle’s make, model year and mileage, as well as the reason for replacement.

• Retain copies of any invoices and statements for six months and the replaced converters for 15 days (converters must be identified or marked as to which customer’s car they came from). The most significant difference between states is the length of time needed to keep documentation – California and New York require paperwork to be kept for at least four years.


When selecting and installing a converter, the catalog can be your best friend to keep the car compliant with emissions regulations. Below are the basics you should follow, but always check with your emissions supplier’s catalog to make sure the replacement converter is properly sourced and installed.

• Install the converter in the same location as the original.

• Install the same type of converter as the original (oxidation, 3-way or 3-way-plus oxidation (dual-bed)). This information is sometimes available on the emissions tune-up label or from the manufacturer’s application catalog.

• Install the proper converter for the vehicle, as determined and specified by the converter manufacturer. There are engine size and vehicle weight limitations which make it inappropriate to install specific converters on certain vehicles. Newer vehicles with On-Board Diagnostic (OBD) systems may not always operate properly with certain aftermarket products. Therefore, the catalog should always be consulted for the correct application.

• The converter must always be connected to any existing air injection components

• Install any other required converters the vehicle would have originally come with unless the converter manufacturer has stated in writing that the aftermarket converter is designed to replace more than one converter

• For new aftermarket converters, the installer must fill out the warranty information card supplied by the manufacturer and give it to the vehicle owner or operator.


Violating the EPA rules is a breach of federal law since noncompliance is likely to increase the amount of pollution coming out of the vehicle. Penalties for violations by individuals, service or repair shops, or fleet operators can be up to $2,500 per violation (Each improper installation is considered a violation.). Additionally, new-car dealers can be penalized up to $25,000 per violation. Any person who causes a violation could be subject to the same penalty as the technician.

New York State Environmental Conservation Law regarding catalytic converter installation mandates a minimum penalty of $500 for a first violation and up to $26,000 for each subsequent offense. Failure to maintain complete records or submit reports may also result in a violation

For vehicles in California and other states that require the California Air Resources Board (CARB)-mandated emissions equipment, the rules are different. All of the same mandates apply, but they are much stricter about the replacement converter being CARB-compliant. Also, the CARB rules are based on a one-for-one replacement strategy, and the addition or consolidation of converters is forbidden

It is important to check local and state laws before installation. New York, for instance, enacted a ban on installing used catalytic converters on vehicles.


When the stock market goes down, the price of precious metals goes up. This has caused a surge in catalytic converter theft. The consequences for the poor vehicle owner who has had his converter stolen far outweigh the scrap value of the cat that was snatched.  

Most of the thefts are done with a battery-powered reciprocating saw, and the most likely targets are SUVs and pickup trucks with plenty of ground clearance. Toyota 4runners are one of the more popular vehicles that are targeted by thieves because it has a relatively large (and valuable) converter and plenty of ground clearance.

There have been a few instances where someone has caught a thief red-handed stealing their converter.  There have also been a few instances of someone getting into their vehicle, starting it up and driving over the thief underneath (accidentally, of course!).  In one routine traffic stop, the police discovered over a hundred sawed off converters in the back of a utility van.  Apparently, the thief was on his way to the metal recycler to hock his stolen goods.

Local and state governments are attempting to deal with the issue by enacting new laws that require metal recyclers and scrap dealers to obtain identification from anyone selling catalytic converters, and to store the converters for a specified period of time (15 to 30 days) in case they turn out to be stolen.  

Another technique that’s being tried in some areas is to engrave the vehicle’s VIN number on the converter shell. This creates a positive means of identification that can be used to identify a converter and match it to a vehicle. Of course, if the number is engraved onto the heat shield, all the thief has to do is cut off the exterior shield to get rid of the evidence.  Or, the thief might just grind off the engraved number to hide it or make it impossible to read.

Installing a skid plate under a 4×4 truck or Jeep is another step that can deter converter thieves.  These flat steel plates attach to the underside of the vehicle to protect the drivetrain and exhaust system from the hazards of off-road driving.  They create an effective barrier that prevents access to the converter.  But they can be unbolted (unless you weld one or two of the bolt heads to the plate). 

You May Also Like

How To Diagnose Electrically Controlled Thermostats

Today’s thermostats need to work just as well in tropical heat as in arctic cold. Do you understand their differences?

An electrically controlled thermostat still uses expanding wax, but it controls the temperature of the wax. To do this, it uses a heater coil surrounding the wax capsule — no fancy stepper motors or plungers.

When the heater or driver circuit fails on an electronically controlled thermostat, the thermostat becomes a conventional thermostat and will not cause the engine to overheat. However,  the engine will know it has failed and will generate a code.

GM Catalytic Converter Break-In Information

A service engine soon light may be experienced on low-mileage vehicles.

Diagnosing P0420 Or P0430 DTCs with Catalytic Converters

It’s important to understand the basics of catalytic converter chemistry and how catalytic converter failures are diagnosed.

Exhaust Repair Options

If a replacement does not meet or exceed the flow characteristics of the original, it could mean more than a loss of power.

Catalytic Converters: Efficiency Code Diagnostics

Understanding catalytic converter efficiency codes can be a long road to a happy customer or an expensive comeback.

Other Posts
How-to Complete Emissions Monitors Faster

This video will focus on how a product like CAT COMPLETE can improve the chances of completing the monitors faster. This video is sponsored by Rislone.

Standard Motor Products Expands Emission Control Program

SMP’s program features more than 3,500 parts, including EVAP, EGR and positive crankcase ventilation products.

Forecast: 80% Drop In U.S. Transportation Emissions By 2050

NREL’s study highlights rapid adoption of zero-emission vehicles as crucial for an 80% emissions reduction.

Understanding Emissions

Modern EVAP systems are selective with how they vent vapors back into the engine. Sponsored by Standard.