P0431: Catalyst 1 Efficiency Below Threshold Bank 2
A generic powertrain (engine and transmission) trouble code, same meaning on every brand.
Yes - no driveability effect, but an emissions test will fail.
Symptoms
- Check engine light
- Emissions test failure
- No change in how the car drives
Likely causes, most common first
- Bank 2 warm-up converter aged
- Exhaust leak on that bank
- Oxygen sensor on bank 2 inaccurate
- Contamination from oil or coolant
Read P0431 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
P0431 is the bank 2 counterpart of P0421 and appears only on engines with two cylinder banks. Since both converters have done the same mileage under the same conditions, one failing usually means the other is close behind.
That matters when budgeting. Some V6 and V8 exhaust designs put both warm-up converters in a single assembly with the manifolds, so the practical repair covers both banks at once whether or not both have set a code.
Repair options and cost
Typical US independent-shop ranges, parts and labor. Dealers run higher; regional labor rates vary.
Owner reports mentioning P0431
“VW Tiguan lost significant acceleration while driving on the highway. Vehicle check engine light came on. Felt like vehicle was going to stall and decelerated to a below highway required speed. Vehicle was inspected by a VW authorized service center and . Verified GFF found DTC's P0431, P04F0, P24D6, and P2101 were in fault mode. Significant oil leak also occurred. Failed component was crankcase pressure regulator and lower oil pan and gasket (due to increased pressure from failed PCV valve.) This was of great concern as the deceleration was significant while on the highway which could cause potential life threatening accidents.”2022 Volkswagen Tiguan · Apr 2025
“2006 jeep wrangler sport less then 60,000 miles on it and keeps getting service code p0431 p0431-catalyst warm up efficiency below threshold all 4 oxygen sensors replaced and still getting code. *tr”2006 Jeep Wrangler · Sep 2010 · 57,000 mi
Cars that report P0431 most often
Based on mentions of this code in NHTSA owner complaints.
Frequently asked questions
Can I drive with P0431?
Yes - no driveability effect, but an emissions test will fail.
How much does it cost to fix P0431?
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 P0431. 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.