EngineLightCodes
Powertrain code

P0430 Catalyst System Efficiency Below Threshold Bank 2

Severity
Fix soon
Typical repair cost
$90–$1,980
Do it yourself
Possible, medium
Shop time
0.5–3 hours

Your catalytic converter on bank 2 isn't cleaning the exhaust as well as it should. Bank 2 is the side of a V6 or V8 engine without cylinder 1. An exhaust leak or a lazy oxygen sensor can cause this code too.

How the engine computer detects it

Like P0420, but for the catalyst of bank 2, so only on V and boxer engines with one catalyst per bank; Y-pipe systems with a shared catalyst report P0420 only. The module compares the oxygen sensors before and after the bank 2 catalyst – a good catalyst smooths the rear signal. GM checks on overrun and sets the code on the first trip if the ratio falls below 0.35; Ford evaluates an index ratio or fuel integration and usually needs several trips. The monitor only runs warm, in closed loop and without misfire, fuel or sensor faults.

Written from public technical sources and not yet checked by a mechanic. How we write these pages

Symptoms

  • Check engine light on, otherwise often no change in driving
  • Emission test failed (higher HC, CO, NOx)
  • Rattling or loss of power if the catalyst has broken up

Common causes

  1. Catalyst aged or poisoned (oil consumption, silicone, coolant) Most likely
  2. Catalyst overheated by misfire or rich running Possible
  3. Rear oxygen sensor sluggish, dirty or unsuitable Possible
  4. Exhaust leak ahead of or at the rear sensor Possible

How to diagnose P0430

  1. Confirm which side of your engine is bank 2. It's the bank without cylinder 1.
  2. Fix misfire and fuel trim codes first. If P0420 is also stored, both converters are affected, which points to a shared cause like oil burning.
  3. Check for exhaust leaks near the rear oxygen sensor on bank 2.
  4. Compare the rear oxygen sensor readings on both banks with a scanner. A rear sensor that switches as fast as the front one means the converter is weak.
  5. Replace the bank 2 converter with a part approved for your state.

Vehicles that report P0430 most

VehicleYearsReportsMedian miles
Honda Pilot2016–20204440k
Ford F-1502011–20201661k
Honda Odyssey2002–20197—
Ford Explorer2015–20194—
Mercury Mountaineer19983—
Ford Taurus2004–20143—
Dodge Durango2005–20143—
Acura MDX2016–20183—
Lincoln MKX2016–20183—

Counts of owner complaints to the NHTSA that mention P0430 (132 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.

Reading the code

P
Powertrain
0
Generic (SAE) code
4
Auxiliary emission controls
30
Specific fault

Questions drivers ask

Can I drive with code P0430?

Yes, the car usually drives normally. It will likely fail an emissions inspection in states that scan the OBD system, and a converter that is breaking apart can rattle or block the exhaust.

Will my car pass an emissions inspection with P0430?

Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.

Will P0430 clear by itself?

The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.

Can I fix P0430 myself?

Often yes, with an OBD-II scanner and basic tools. Difficulty: medium. Start with the cheapest checks before replacing expensive parts.

Often reported together

Codes that owners mention in the same NHTSA complaints as P0430. They can point to a shared cause, so it's worth checking them together.

This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.