Code Definition

P1127 — Long Term Fuel Trim B1 System Too Rich

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Audi

About P1127

P1127 is a manufacturer-specific powertrain diagnostic trouble code recorded for Audi vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1127 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The Engine Control Module (ECM) continuously adjusts fuel delivery to maintain the correct air to fuel ratio, and long term fuel trim represents the learned correction stored over time. DTC P1127 is set when the long term fuel trim for Bank 1 reaches a negative correction limit because the ECM is continually subtracting fuel to compensate for a rich running condition across the entire speed and load range. A rich mixture means the engine is receiving too much fuel or too little air, which forces the oxygen sensor feedback to command large negative trim values. When this code is stored the driv...

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