P1127moderate severityPowertrain
Long Term Fuel Trim System Too Rich Bank 1
on 2009 Audi TT 3.2L V6 · AWD
What this code means
The ECU detected that the long-term fuel trim for Bank 1 has exceeded the maximum rich correction limit. The engine is consistently receiving too much fuel and the adaptive system cannot compensate further.
Symptoms
- Check Engine Light
- Rich exhaust odor
- Black exhaust smoke
- Poor fuel economy
- Rough idle
Common causes
- Leaking fuel injectors
- Faulty fuel pressure regulator (excess pressure)
- O2 sensor reading false lean
- EVAP purge valve stuck open
- Coolant temperature sensor reading colder than actual
Diagnostic steps
- Monitor long-term and short-term fuel trims
- Test O2 sensor response time
- Check fuel pressure with gauge
- Inspect EVAP purge valve
- Test coolant temperature sensor
Repair notes
Identify and repair the root cause of excess fuel delivery on Bank 1.
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