Code Definition

P1124 — Fuel mixture LEAN, long term fuel trim

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

About P1124

P1124 is a manufacturer-specific powertrain diagnostic trouble code recorded for Hyundai 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.

P1124 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) monitors exhaust oxygen content through the upstream heated oxygen sensor and trims fuel delivery using short term and long term fuel trim. DTC P1124 is set on Hyundai and Kia vehicles when the long term fuel trim for Bank 1 reaches its maximum positive (add fuel) correction because the air fuel mixture is persistently lean. The ECM has been adding as much fuel as its adaptive authority allows, yet the mixture remains leaner than the target stoichiometric ratio, indicating either unmetered air entering the engine or a shortfall in fuel delivery. Typical driveabi...

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