Emissions code
P0430: Catalytic converter not working well (bank 2)
This is the same check as P0420 but on the second side of a V-style or flat engine. The sensor after the converter is reading too much like the one before it, so the converter on that side is not cleaning the exhaust enough.
- Safe to drive?
- Usually yes, for now
- Most common cause
- Worn converter on the bank 2 side
Fine to drive for a short time, but fix it soon; stop if the check-engine light flashes or the engine shakes.
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $250 | $1,400 |
| Labor: 1.2 to 2.5 hours × $125 to $175 an hour | $150 | $438 |
| Fees: shop supplies, disposal, diagnostics | $0 | $40 |
| Total, rounded | $400 | $1,900 |
The hourly rate is the BLS Occupational Employment and Wage Statistics, May 2025 average pay for this trade in Boston, $31.54 an hour, times 4 to 5.5 to cover what a shop bills (overhead, tools, insurance, profit). Parts are a band from budget aftermarket to the manufacturer part. Full method.
Not a repair shop, estimates only. Typical range, estimate. Not a quote. Your car, parts and shop change the number.
This is the range for the most common fix, catalytic converter replacement. Which repair your car needs depends on a proper diagnosis.
What you may notice
- Check-engine light on
- Failed emissions test
- Less power when climbing hills
Common causes, most likely first
- Worn converter on the bank 2 side
- Rear oxygen sensor on that side reading wrong
- Exhaust leak before or at the converter
- Past misfires or oil burning that hurt the converter
Check this first
Find out which side is bank 2 on your engine and check that side's exhaust joints for leaks. Ask whether both converters are being quoted or just one.
Other repairs that sometimes fix P0430
| Repair | Typical range, Boston |
|---|---|
| Oxygen sensor replacement (one sensor) | $110 to $370 |
| Diagnostic scan (check engine light) | $60 to $290 |
Before you pay
- Ask the shop what test showed this part is the cause, not just that the code appeared.
- Ask for parts and labor listed separately, and for the hours.
- Ask for a written OK before any extra work. Massachusetts rules require written authorization before repairs.
Got a quote already? Check it against the range. Want to see if your car has a recall tied to this problem? Check recalls by VIN.
Need to read a code yourself? OBD-II scanners on eBay (affiliate link, disclosure).
P0430 questions
What does bank 2 mean?
It is the side of the engine that does not hold cylinder 1. Your shop can tell you which side that is on your model.
If only one side is flagged, should I replace both converters?
Usually only the flagged one is replaced, but if both banks are old a shop may suggest both. Ask for the live sensor numbers on each side.
Can a bad spark plug cause this?
Indirectly. Raw fuel from a misfire can overheat and damage the converter, so any misfire code should be fixed before or with the converter.
How much does it cost to fix P0430?
The most common fix, catalytic converter replacement, has a typical range of $400 to $1,900 in Boston. It is an estimate built from parts prices and local labor wages, not a quote. Your car and shop change it.
P0430 repair cost by city
Related codes
- P0420: Catalytic converter not working well (bank 1)
- P0158: Downstream oxygen sensor reads high voltage (bank 2)
- P0300: Random or multiple cylinder misfires
More emissions codes
Code meaning written in our own words. Some codes mean different things on different makes, so check your scan tool or manual. Not a repair shop, estimates only.