P2424
HC Adsorption Catalyst Efficiency Below Threshold Bank 2
Catalytic converter / emissions
Generic OBD-II
Medium
What it means
P2424 means the hydrocarbon-adsorbing catalyst on bank 2 is no longer storing and treating exhaust hydrocarbons efficiently enough to meet the ECM's threshold. It is an emissions fault, so the car runs normally but will fail an emissions test. The cause is often a worn converter, but an upstream misfire, rich mixture, or exhaust leak can damage it or fake the reading — check those first.
Medium
Can I keep driving? Yes — the car runs and drives normally. This is an emissions-efficiency fault, so the main consequences are the warning light and an emissions-test failure.
Common symptoms
What you'll notice
- Check-engine light on
- Fails an emissions/readiness test
- Usually no noticeable change in how the car runs
- Possible faint exhaust smell after a cold start
Common causes
Most likely first
- Aged or failed hydrocarbon (HC) adsorber/catalyst on bank 2Likely
- Exhaust leak upstream of the converter skewing readingsCommon
- Upstream fault (misfire or rich mixture) that has damaged the catalystCommon
- Faulty oxygen sensor feeding the efficiency calculationLess often
- Overheated catalyst from prolonged rich runningLess often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and fix any misfire, fuel-trim, or oxygen-sensor codes first — they can cause or mimic this fault.
- Inspect the exhaust for leaks between the engine and the converter.
- Verify the upstream and downstream oxygen sensors are switching correctly.
- Confirm the converter is genuinely below efficiency with a scan tool before condemning it.
- Replace the HC adsorber/catalyst if it has failed, then clear the code and re-test.
FAQ
Quick answers
Is it safe to drive with P2424?+
Yes, it does not affect safety or normal running. It means the converter's hydrocarbon-storing efficiency is low, so the car will fail emissions and pollutes more.
Can I just clear P2424?+
It will return once the monitor re-runs unless the underlying cause — a worn converter or an upstream fault — is repaired.
Related codes
Often seen with P2424
Read & clear P2424 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX