The Lemon IndexThe catalytic converter on bank 1 isn't cleaning the exhaust as well as it should. Full P0420 page
12 owner complaints · the #2 code Hyundai Tucson owners name · 10% of Hyundai Tucson complaints that name a code (every car: 2.3%)
2005–2020 Hyundai Tucson · most: 2019 (6), 2020 (2), 2016 (2)
Hyundai Tucson owners named P0420 in 12 complaints to the U.S. government (NHTSA), most often on the 2019, 2020 and 2016 model years. The part they name most is the catalytic converter (7 complaints). Complaints are owner reports, not proof of a defect.
Hyundai Tucson model years that report P0420
Owner complaints naming P0420, by model year. Raw counts: years that sold more get more complaints, so this is each model year's record, not a failure rate.
What owners say caused it or fixed it
The most-named part is the catalytic converter, in 7 of the 12 complaints (58%). 7 of those mention it being replaced or repaired, and 4 say the problem came back afterwards. Next: intake manifold or gasket (2), oxygen (O2) sensor (2) and spark plugs (2).
- Catalytic converter7 complaints7 mention a repair or replacement, 4 of them say the problem came back · what Hyundai Tucson owners paid
- Intake manifold or gasket2 complaints2 mention a repair or replacement · what owners paid
- Oxygen (O2 / air-fuel) sensor2 complaints2 mention a repair or replacement, 1 of them says the problem came back · what owners paid
- Spark plugs2 complaints2 mention a repair or replacement, 1 of them says the problem came back · what owners paid
- Head gasket or coolant in a cylinder2 complaints1 mentions a repair or replacement, 1 of them says the problem came back · what owners paid
Counted from the owners' own words: a part counts when a sentence names it with a cause or repair word. What owners wrote, not a diagnosis. A shop should confirm the cause before replacing parts.
Symptoms owners describe with P0420
75% of these complaints say the check engine light came on.
- Loses power or goes into limp mode42%5 of 12 complaints
- Shakes, runs rough or misfires25%3 of 12 complaints
- Uses or leaks oil25%3 of 12 complaints
- Warning lights and electrical faults17%2 of 12 complaints
- Stalls or shuts off17%2 of 12 complaints
Share of the complaints naming P0420 whose text also describes each problem. A complaint can describe more than one.
Repair costs
Hyundai Tucson catalytic converter replacement cost
Recalls on these Hyundai Tucson years
- Engine · 2017 · issued 2021
The connecting rod bearings inside the engine may wear prematurely, which can result in engine damage. NHTSA 21V727000 - Transmission & drivetrain · 2016 · issued 2016
Certain driving conditions and high temperatures may cause the vehicle to not move if the accelerator pedal is pressed and released repeatedly. NHTSA 16V628000
2 recalls for the same systems (engine and powertrain) on the Hyundai Tucson model years above. A recall for the same system isn't proof it's behind P0420. Recall work is free at any dealer: check a VIN at nhtsa.gov/recalls or with our VIN check.
Keep going
- P0420: meaning, causes and every car that reports it
- Hyundai Tucson reliability by year
- 2019 Hyundai Tucson problems and recalls
Other codes Hyundai Tucson owners report
P0420 on other cars
Kia Soul (80) · Nissan Altima (19) · Ford Focus (16) · Honda Odyssey (11) · Ford F-Series (10) · Honda Pilot (10)
The details
How we count
We read every owner complaint in the NHTSA file whose text names this trouble code, and count the ones filed about this model (matched by the make, model and model year on the complaint). Mileage is what the owner entered on the form.
Parts: a complaint counts for a part when one of the owner's own sentences names that part together with a cause word (failed, bad, diagnosed, caused by, leaking ...) or a repair word (replaced, repaired, new, reprogrammed ...). "Came back" means the same complaint also says the problem returned or the repair didn't fix it. These are counts of what owners wrote, not a diagnosis, and one complaint can name several parts.
Complaints are reports, not proof of a defect, and most owners never file one. Popular models get more complaints, so the counts are not a failure rate. The code meaning is the standard SAE J2012 definition in our own words, or the carmaker's meaning where we verified it for that make.
What P0420 means
The catalytic converter on bank 1 isn't cleaning the exhaust as well as it should. The car usually drives normally, but it can fail an emissions test.
Drive on, get it checked. You can usually keep driving. Have the code read at your next service or within a few weeks.
- Worn-out catalytic converter
- Faulty downstream O2 sensor
- Exhaust leak
- Misfires or oil burning that damaged the converter
Check the complaints yourself
NHTSA complaint numbers (search them at nhtsa.gov): 11673527, 11653401, 11633642, 11629617, 11608382, 11603611, 11571134, 11568783, 11501904, 11464602, 11442536, 11415689.
Quick answers
What does P0420 mean on a Hyundai Tucson?
Catalyst System Efficiency Below Threshold (Bank 1). The catalytic converter on bank 1 isn't cleaning the exhaust as well as it should. The car usually drives normally, but it can fail an emissions test.
Which Hyundai Tucson years have the most P0420 complaints?
In complaints to NHTSA, owners of the 2019 (6), 2020 (2), 2016 (2) Hyundai Tucson named P0420 most (12 complaints in all, 2005–2020). Raw counts, not a failure rate.
What fixes P0420 on a Hyundai Tucson?
Owners most often name the catalytic converter (7 of 12 complaints), then intake manifold or gasket and oxygen (O2) sensor. That's what owners wrote, not a diagnosis: have a shop confirm the cause with a scan and tests before replacing parts.
Can I drive my Hyundai Tucson with P0420?
Drive on, get it checked. You can usually keep driving. Have the code read at your next service or within a few weeks.
Sources: NHTSA owner complaints that name P0420 on the Hyundai Tucson, counted by The Lemon Index; NHTSA recalls; repair bills owners named. Meanings: SAE J2012 in our own words. Owner reports, not a diagnosis or repair advice for your car.