P0430 is the Bank 2 equivalent of P0420. The catalytic converter on the engine bank opposite cylinder 1 isn't converting exhaust gases efficiently enough. The ECU detects this by comparing the upstream and downstream O2 sensor signal patterns on Bank 2.
DTC/P0430·Honda
P0430 on Honda: Causes, Symptoms and Fix Cost
Quick Answer
Moderate SeveritySafe to drive (short-term)Honda
P0430 on a Honda is the Bank 2 equivalent of P0420. The catalytic converter on the engine bank opposite cylinder 1 isn't converting exhaust gases efficiently enough. The ECU detects this by comparing the upstream and downstream O2 sensor signal patterns on Bank 2.
Repair cost on Honda€90 - €1710
What does P0430 mean on a Honda?
Honda Civic
2006-2024Most Honda Civics are inline-4 and won't trigger P0430 (Bank 2 doesn't exist). If you see P0430 on a Civic, double-check the scan tool reading. The Si model with the K20 or L15B7 turbo are still single-bank engines. Only the rare V6 Civic (older generations) would show P0430.
What causes P0430 on a Honda?
Beyond the generic causes listed on the main P0430 page, these are the Honda-specific patterns we see most often:
Honda CivicExtremely rare on Civics since most are inline-4 (single bank)
Honda CivicPossible scan tool misread. Confirm with a second scanner
How to diagnose P0430 on a Honda with OBD2
Follow these steps to pinpoint the root cause of P0430:
- Check for companion codes (misfires, lean/rich, O2 heater codes). Address those first as P0430 may be secondary
- Graph Bank 2 upstream and downstream O2 sensors at steady cruise (2,000-2,500 RPM). Upstream should oscillate 0.1-0.9V rapidly. Downstream should be flat around 0.4-0.6V on a healthy converter
- If downstream sensor mimics upstream oscillations, converter is failing
- Check downstream O2 sensor response time. If switching takes over 300ms (lean-to-rich or vice versa), sensor itself is sluggish and may be the cause
- Inspect exhaust manifold, converter connections, and piping for leaks (listen for ticking/hissing on cold start)
- On high-mileage vehicles, check oil consumption rate. Oil burning contaminates converters
How much does P0430 cost to fix on a Honda? (EUR)
Estimated repair costs on a Honda (Honda parts and labour typically run 10% below the average for this code).
Prices estimated as of May 2026. Costs vary by region, vehicle, and shop.
Related codes that often appear with P0430 on Honda
These codes commonly cluster with P0430 on Honda vehicles:
FAQ: P0430 on Honda
What is the difference between P0420 and P0430?
Same problem, different engine banks. P0420 is Bank 1 (cylinder 1 side). P0430 is Bank 2 (opposite side). Four-cylinder engines only get P0420. P0430 appears on V6, V8, and boxer engines.
Can a bad O2 sensor cause P0430?
Yes. The downstream O2 sensor on Bank 2 is what the ECU uses to judge converter efficiency. If sluggish or contaminated, it can trigger P0430 with a healthy converter. Always test the sensor before assuming converter failure.
Will P0430 cause my car to fail emissions?
Yes. P0430 directly relates to catalyst performance, a primary emissions criterion. The check engine light alone is an automatic fail in most testing regimes.
Can I just clear P0430 and hope it goes away?
You can clear it, but it returns within 1-3 drive cycles if the root cause persists. The ECU runs the catalyst efficiency test automatically. Clearing before an emissions test doesn't work either because readiness monitors need time to complete.
Looking for the full P0430 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0430 guideSkanyx · Honda
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