The dealer diagnosed it and says it got tripped by catalytic converter and rear oxygen sensor. The total estimate was around $2000. The blue book value on his car is around that amount. Is there a way to repair this with less cost and pass inspection?

  • 1
    Do you know the exact code(s)? Mar 23, 2011 at 20:35
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    P0430 = Catalyst System Efficiency Below Threshold (Bank 2) P0139 = O2 Sensor Circuit Slow response ( Bank 1, Sensor 2) P0138 = O2 Sensor Circuit High Voltage ( Bank 1, Sensor 2)
    – zkarthik
    Mar 25, 2011 at 14:25

2 Answers 2


I am assuming that you are in NC based on your profile. You can obtain a wavier if you spend at least $200 I will list the rest of the requirements at the end of this post.

I am leery that the catalytic converter is bad, the ECM (the cars computer) uses the post cat O2 sensor to determine cat efficiency and if it's bad as they said it could cause the computer to falsely fail the cat.

I would replace the O2 sensor first then clear the codes and see if the Cat still fails. Following the rules below the O2 sensor replacement will likely be enough to qualify for the waiver and buy you at least another year


You may be able to obtain a waiver if your car failed the emissions inspection and the part needed to fix the problem is unavailable. This is documentation provided by DMV License and Theft stating that you have tried in good faith to replace a missing component or part on your vehicle.

You must first obtain letters from a dealership, parts store and salvage yard stating the part is no longer manufactured or obtainable. If DMV License and Theft is also unable to locate the part, a waiver allowing your vehicle to pass the emissions test will be issued. On the other hand, if DMV locates the part, the vehicle-owner must comply, and the parts waiver will be denied.

If you purchased the necessary parts and made the recommended repairs, but the car still fails the emissions inspection a waiver may also be issued. However, the owner/operator must spend the required waiver amount in parts and/or labor in order to bring the vehicle within compliance standards. If the owner/operator can provide appropriate documentation of expenditures, the vehicle may be issued a waiver. Waiver expenditure amounts will not apply to the reconnection of tampered or removed exhaust emissions control devices.

A minimum expenditure of $200.00 is required for model year 1996 and newer vehicles. A recognized repair technician is considered to be someone who is professionally engaged in vehicle repairs or employed by a business whose purpose is vehicle repair or possessing nationally recognized certification for emission-related diagnostics and repair.

Criteria needed to get a waiver:

  • The vehicle must pass the safety inspection.

  • The vehicle must have all emissions components appropriate to the make, model, year, series, and engine size properly installed and visually operating.

  • The vehicle must fail the initial OBD emissions test although all the emissions components are installed.

  • The vehicle owner must attempt to obtain repairs appropriate to correct the cause of failure and bring the vehicle within compliance standards. All repair receipts must be kept to be used as a part of the vehicle owner's waiver request. These receipts must be itemized, dated and include the name of each part or component.

  • The vehicle owner must have the repairs performed after the vehicle fails the first emissions test and completed within 45 days of the initial inspection and prior to the final inspection.

  • The vehicle owner is advised that only those repairs made to correct emissions problems will be counted for a waiver and must bring the vehicle to emissions compliance standards.

  • The vehicle owner must have the catalytic converter replaced if the unleaded fuel restrictor has been tampered or removed. The fuel restrictor must also be repaired or replaced.

  • The vehicle owner is advised that the cost of tampered or removed emissions control components or device, or their cost for reconnection, is not acceptable.

  • The vehicle owner is advised that conducting diagnostics of the vehicle is not acceptable unless the recommended work is performed on the vehicle.

  • The vehicle owner is advised that a written Denial of Dealer Warranty Coverage is required from the manufacturer or authorized dealer if the vehicle is still within the statutory age and mileage requirements as set forth in Section 207(b) of the Federal Clean Air Act.
  • The vehicle must fail only the OBD portion of the re-inspection after repairs have been made.

Once the above regulations have been met, the vehicle and all receipts must be brought to the local License and Theft Bureau for visual inspection. Waivers will normally be issued between 8a.m. and 10a.m. Monday through Friday except on state holidays.

Source NC DMV


These two links give some diagnostic information on catalytic converters and O2 sensors:

If the 02 sensor is working properly and thus properly condemning the catalytic converter, one option is to have an exhaust shop replace just the converter. The factory exhaust pipe with the converter is usually very expensive, but an exhaust shop may be able to cut out the converter and fit in a (much cheaper) aftermarket one.

Yes, this is kind of a duct tape solution, but I think the price point of the car warrants it. However, I have seen some really shoddy exhaust work before. If you do go this route, try to find some reviews or get some recommendations.

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