Heated Catalyst Efficiency Below Threshold (Bank 2)
The P0433 code means the vehicle's onboard diagnostic system has detected: Heated Catalyst Efficiency Below Threshold (Bank 2). This is a moderate severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- hard
- Estimated cost
- $400 - $1400 (parts and labor)
Reads enhanced codes and shows real-time O2 sensor data. Verify the cat is actually bad before dropping $1,000+ on a replacement.
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Common Symptoms
- Check Engine Light illuminated
- Sulfur smell from exhaust
- Slight decrease in fuel economy
- Failed emissions test
Probable Causes (Ranked by Likelihood)
- Degraded heated catalytic converter on Bank 2 Very High
- Bank 2 catalyst heater circuit failure High
- Engine misfire contaminating the Bank 2 catalyst Moderate
- Faulty Bank 2 downstream O2 sensor Low
Step-by-Step Diagnostic Procedure
-
Check for catalyst heater circuit codes on Bank 2
-
Compare Bank 2 upstream and downstream O2 sensor activity
-
Verify Bank 2 catalyst heater operation by measuring current draw during cold start
-
Check for exhaust leaks and misfire codes on Bank 2
-
Replace the Bank 2 heated catalyst if all other checks pass
Frequently Asked Questions
Can I drive with code P0433?
Yes. The Bank 2 heated catalyst is underperforming but the vehicle drives normally. Emissions will be higher during cold starts.
Is P0433 the Bank 2 version of P0423?
Yes. P0423 refers to Bank 1 heated catalyst efficiency and P0433 refers to Bank 2. The diagnostic approach is identical but applied to the opposite exhaust bank.
Do I need to replace both bank converters?
Only if both are failing. If only Bank 2 has set a code, replace only the Bank 2 converter. However, if both are similar age, proactive replacement of both may save labor costs.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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