What this code means

The NOx storage catalytic converter on bank 1 is not efficiently reducing nitrogen oxides.

Symptoms

• Check engine light
• Failed emissions test
• Reduced fuel economy

Common causes

• Degraded NOx trap
• Sulfur contamination
• Exhaust leak before sensor
• Faulty NOx sensor

Diagnostic steps

1. Read freeze frame data
2. Check NOx sensor readings upstream and downstream
3. Inspect for exhaust leaks
4. Perform desulfation procedure if applicable

Repair notes

Replace NOx trap if desulfation fails. Check upstream components for causes of contamination.

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