Hyundai code
P0420: on a Hyundai
How much to fix P0420 on a Hyundai? Typically $430 to $2,325 for catalytic converter replacement, the most common fix. This is an estimate, not a quote.
Hyundai has had several engine recalls and warranty extensions on its four-cylinder engines. P0420 on one of those cars can be linked to oil use or misfires, so check the recall status first.
General meaning of P0420: The computer compares the oxygen sensor before the catalytic converter with the one after it. On this code the two readings look too alike, which suggests the converter is not cleaning the exhaust as well as it should on the side with cylinder 1. See the full P0420 page.
Models to know about
| Model | Years | What to know |
|---|---|---|
| Elantra | 2011 to 2020 | Often paired with other engine codes. |
| Sonata | 2011 to 2019 | The 2.4 Theta II has recalls; check your VIN. |
| Tucson | 2010 to 2020 | Mostly converter or sensor. |
| Santa Fe | 2010 to 2019 | Same engines as the Sonata. |
Common causes on a Hyundai
- Misfire or oil burning from a worn engine.
- Rear oxygen sensor aging.
- Converter failure from earlier misfire damage.
- Exhaust leak at the flex joint.
NHTSA's public complaint file shows how owners describe this kind of trouble: the 2013 Hyundai Sonata has 1,916 complaints on file, and 390 of them use wording like catalytic, check engine, P0420, oil; the 2014 Hyundai Elantra has 387 complaints on file, and 93 of them use wording like catalytic, check engine, P0420, oil. Complaints are owner reports, not proof of a cause.
Check this first
- Run your VIN on the recall page. Hyundai has engine campaigns on some model years.
- Check oil level every two weeks.
- Ask for misfire counts in live data.
Wide range: this job varies a lot. Itemize your quote for a better answer.
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $300 | $1,900 |
| Labor: 1.2 to 2.5 hours × $110 to $150 an hour | $132 | $375 |
| Fees: shop supplies, disposal, diagnostics | $0 | $40 |
| Total, rounded | $430 | $2,325 |
The hourly rate is the BLS Occupational Employment and Wage Statistics, May 2025 average pay for this trade in the US, $27.13 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. In California and New York, parts cost more because those states require a California-certified converter. Full method.
Not a repair shop, estimates only. Typical range, estimate. Not a quote. Your car, parts and shop change the number.
Converters are the pricey part. Hyundai dealers may cover some engine failures under warranty extensions, which is worth checking before any repair.
Other repairs that may be involved
| Repair | Typical range, US |
|---|---|
| Catalytic converter replacement | $430 to $2,325 |
| Oxygen sensor replacement (one sensor) | $100 to $350 |
Questions to ask the shop
- Is there a recall on my VIN?
- Is the oil level normal?
- What is the warranty on the part?
Got a quote already? Check it against the range. Wondering if a recall touches this problem? See Hyundai recalls by model or check a VIN.
P0420 on a Hyundai: questions
Does a recall fix P0420?
Not by itself. But an engine recall may cover the cause.
Should I replace sensors first?
Only if tests support it.
How much does it cost to fix P0420 on a Hyundai?
The most common fix, catalytic converter replacement, has a typical range of $430 to $2,325 across the US. That is an estimate built from parts prices and local labor wages, not a quote. Your model, engine and shop move it.
P0420 on other makes
Sources
- NHTSA complaints, 2013 Hyundai Sonata
- NHTSA complaints, 2014 Hyundai Elantra
- NHTSA recall lookup by VIN
- US federal emissions defect warranty rules (40 CFR part 85, subpart V)
Written from public NHTSA data, owner-reported patterns and general repair knowledge, in our own words. Model lists are examples, not a full list, and patterns are not a diagnosis. Prices updated October 2026. Not a repair shop, estimates only.