Catalytic Converter Theft and the Smog Check Program

Catalytic converter thefts have increased at an alarming rate, leaving vehicle owners to deal with costly and time-consuming repairs. As a result, consumers are seeking ways to deter thieves with some taking it upon themselves to install homemade or aftermarket theft prevention devices. Unfortunately, improper installation of a theft prevention device may result in a vehicle falling out of Smog Check compliance or, worse, causing irreparable damage to the catalytic converter. Whether an automotive repair dealer (ARD) is replacing a catalytic converter, installing a theft prevention device, or performing a Smog Check on a vehicle equipped with a theft prevention device, following are steps ARDs can take to ensure proper and thorough inspections and repairs.

Converter Replacement

Replacement converters must be either an Original Equipment Manufacturer (OEM) part or an aftermarket part that has been approved by the California Air Resources Board (CARB). The aftermarket converter must be installed so that the CARB Executive Order (EO) number is visible on the shell of the converter. The replacement converter must be validated as appropriate for the vehicle. EO numbers can be validated through CARB’s Aftermarket Catalytic Converter Database at

When installing a replacement converter, it is imperative that the converter is installed in the original vehicle manufacturer location and configuration and the vehicle has the correct number of converters installed, unless changes are acceptable under the EO and made consistent with its provisions. This is especially important for converters that must be welded into the exhaust system. Any variances in installation can result in the vehicle failing its Smog Check.

Theft Prevention Device Installation

Any licensed ARD may install catalytic converter theft prevention devices. Theft prevention devices include steel cages, chains, cables, protective plates and shields. Regardless of the type of theft prevention device, the catalytic converter must not be modified or compromised in any way.

When installing a theft prevention device, the ARD must take care to not weld the device directly onto the converter, to ensure there is adequate visibility of the identification numbers on the catalytic converter, and to confirm there are no restrictions on required ventilation for the converter.

Smog Check Inspections

When performing a Smog Check, the licensed inspector must perform a visual inspection to ensure that the catalytic converter is present, undamaged, unmodified, and installed in the correct location. The inspector must look for the EO number and confirm that the model of aftermarket catalytic converter is approved for the vehicle. (Refer to the Smog Check Manual for additional details.) If the EO number cannot be validated, the vehicle will fail the inspection.

If a theft prevention device has been installed in such a way that the inspector cannot validate the EO number or determine that the catalytic converter is installed properly, the inspector must consult with the customer about options, including removing the theft prevention device for the inspection.

If the inspector finds that the catalytic converter has been damaged or modified to the point where the functionality of the converter is compromised, the inspector must enter “Tamper” or “Modified” into the inspection system. The inspector will need to inform the customer that the vehicle failed the inspection and the catalytic converter may need to be replaced.

If the customer has concerns about the Smog Check inspection results and would like a third party evaluation, they may contact the Smog Check Referee.

Catalytic converter theft has complicated the task of keeping vehicles Smog Check compliant for many consumers. By providing consumers with sound advice about theft prevention options and properly installing theft prevention devices, ARD’s can help consumers prevent catalytic converter theft. By following catalytic converter installation specifications and conducting comprehensive Smog Checks, ARDs can ensure vehicles are safe and Smog Check compliant.

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