P0422: Catalyst 2 Efficiency Below Threshold Bank 1
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Yes - the car drives normally but will not pass an emissions test.
Symptoms
- Check engine light
- Emissions test failure
- Occasional sulphur smell
Likely causes, most common first
- Main catalytic converter worn out
- Downstream oxygen sensor inaccurate
- Exhaust leak between the converter and the sensor
- Oil or coolant consumption contaminating the converter
Read P0422 yourself before paying for diagnosis
A basic Bluetooth OBD-II scanner ($20-40) plugs into the port under the dashboard and shows this code with live sensor data on your phone - useful both for confirming the fix and for talking to a shop from an informed position.
What is going on and how it gets diagnosed
P0422 says the main catalytic converter on bank 1 is not cleaning the exhaust as effectively as it should. Converters do wear out, but they usually wear out for a reason rather than from age alone.
That reason is worth finding first. Misfires push raw fuel into the converter and overheat it; oil consumption coats it; a rich mixture does both. Fitting a new converter to an engine with any of those problems unresolved is the most common way to pay for the same part twice.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Owner reports mentioning P0422
“Diagnostic code failure P0422 Evap system failure had emission testing done recently about two weeks ago . Car was service by Volvo in March 2024 and nonissues . Low mileage on car under 20k This should be recalled as many on online forums are having the same issue . Faulty manufacturing and Volvo should issue recall .”2019 Volvo XC40 · Aug 2024
“Vehicle running sluggish approx. 3 weeks prior. Check engine light warning came on and immediately took vehicle to ford for a diagnostics check. Vehicle had a code p0422, test ran verified evaporative system leak. I was told it was a safety issue and not drivable. Fuel filler pipe was cracked and needed replacement. Ford has prior recalls for this part over the years, although ford did not cover this repair. 1 week prior one of two engine fans went out requiring replacement.”2009 Ford Flex · Jun 2011 · 52,300 mi
“I have had many problems with my 2003 nissan altima 2.5s. Currently excessive oil consumption code p0422 - replaced catalytic converter and pre-cat. *tr”2003 Nissan Altima · Sep 2008 · 127,000 mi
Cars that report P0422 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0422?
Yes - the car drives normally but will not pass an emissions test.
How much does it cost to fix P0422?
Typical US repair costs range from $150 for the simplest fix (exhaust leak repair) to $2,500 in the worst case. The right number depends on which cause your car has - see the causes list.
Related codes
The codes closest to P0422. They often appear together, and telling them apart is usually what narrows the diagnosis.
Definition per SAE J2012 standard nomenclature. Symptoms, causes and costs are editorial guidance - always confirm with a diagnosis of your specific vehicle.