Test TC-14A - System Rich L-Idle ADAP At Lean Limit (DTC 52)

This trouble code may set for several reasons not related to Powertrain Control Module (PCM) electronics. Long-Term Idle Adaptive (L-IDLE ADAP) memory is designed to aid in air/fuel control. Its function is to adapt air/fuel mixture to correct for fuel pressure differences and mechanical changes such as engine wear and mechanical malfunctions.

This trouble code affects O2S system. PCM reaches its operating limit when one O2S indicates a continuous lean exhaust gas mixture. O2S responsible is disabled and other O2S takes over. If both sensors are indicating excessive lean readings, fuel control system goes into open loop mode.

Possible causes of SYSTEM RICH L-IDLE ADAPT AT LEAN LIMIT trouble code are:

• Faulty catalytic converter.
• Faulty EGR valve.
• Faulty fuel pump.
• Faulty injectors.
• Faulty MAP sensor.
• Faulty O2S.
• Faulty fuel pressure regulator.
• Faulty wiring harness or connectors.
• Excessive engine wear.
• Mechanical malfunctions.

Perform tests listed in SYSTEM RICH L-IDLE ADAP AT LEAN LIMIT TESTS table, in sequence until problem causing trouble code is found.