What causes fault code P0433?

• Most likely: Degraded or faulty catalytic converter (Bank 2) • Likely: Exhaust leak upstream of or near the catalyst • Possible: Faulty downstream oxygen sensor • Rare: Faulty catalyst temperature sensor or wiring issues

How do you fix fault code P0433?

STEP 1: Inspect the exhaust system for leaks upstream of the catalyst. STEP 2: Use a scan tool to monitor live data for oxygen sensors. The downstream sensor should show a steady voltage (around 0.5V), not mimicking the upstream sensor's rapid switching. STEP 3: Verify there are no secondary codes for misfires or fuel trim issues. STEP 4: If no other faults are found, replace the catalytic converter (Bank 2) and clear the code.

Powertrain (Engine & Gearbox)Standard EOBD

P0433 - Heated Catalyst Efficiency Below Threshold (Bank 2)

Q: What are the symptoms of fault code P0433?

• Check Engine Light (MIL) illuminated • No noticeable driveability symptoms (usually) • Increased tailpipe emissions • Failed emissions test

Last updated:1 February 2026

Related:Katalysator Bank 2, Oxygen Sensor (Lambda), Avgassystem, Engine Control Module (ECM)

System

Powertrain (Engine & Gearbox)

Related Fault Codes

P0400

Exhaust Gas Recirculation Flow Malfunction

P0401

Exhaust Gas Recirculation (EGR) Flow Insufficient Detected

P0402

Exhaust Gas Recirculation Flow Excessive Detected

P0403

Exhaust Gas Recirculation (EGR) Control Circuit

Technical Description

P0433 is a diagnostic trouble code (DTC) for 'Heated Catalyst Efficiency Below Threshold (Bank 2)'. The ECM monitors the efficiency of the catalyst using oxygen sensors located before and after the catalytic converter. If the rear oxygen sensor's waveform mimics the front sensor's waveform too closely, it indicates that the catalyst is not storing oxygen effectively and its conversion efficiency has dropped below the calibrated limit.

Possible Causes

Degraded or faulty catalytic converter (Bank 2)

Exhaust leak upstream of or near the catalyst

Faulty downstream oxygen sensor

Faulty catalyst temperature sensor or wiring issues

Symptoms

Check Engine Light (MIL) illuminated

No noticeable driveability symptoms (usually)

Increased tailpipe emissions

Failed emissions test

Do you also have
other fault codes?

See how P0433 connects with your other fault codes. Our advanced analysis tool identifies causal relationships and root causes directly.

Analyze multiple codes

P0433 - Heated Catalyst Efficiency Below Threshold (Bank 2)

Related Fault Codes

Technical Description

Possible Causes

Symptoms

Recommended Solution

Workflow

Mechanic's Tip

Do you also have
other fault codes?

P0433 - Heated Catalyst Efficiency Below Threshold (Bank 2)

Related Fault Codes

Technical Description

Possible Causes

Symptoms

Recommended Solution

Workflow

Mechanic's Tip

Do you also have other fault codes?

Do you also have
other fault codes?