Yale 522660-0 – Engine Control Unit (ECU): Long Term Closed Loop Correction Bank 1 Less Than NOR -30% (Rich Engine Operation)

The engine is running in a 'rich' condition (receiving too much fuel or not enough air). The engine control system has attempted to compensate by leaning out the fuel mixture, but it has reached its maximum adjustment limit (-30% to -35%) and can no longer correct the air-fuel ratio.

• Yale and Hyster Forklifts
• Yale VX Series (e.g., GLP050VX, GLP070VX, GLC060VX)
• Hyster FT Series (e.g., S50FT)
• Trucks equipped with Mazda, GM 2.4L, and PSI propane engines

1. 1

   Air Induction System Check: Inspect the air filter and all air breather hoses for obstructions. A severe restriction will choke the air supply, causing a rich condition.

2. 2

   O2 Sensor Monitoring: Use a diagnostic handset or software to monitor the Oxygen (O2) sensors while the engine is running in a closed loop. Ensure the sensor voltage is fluctuating normally.

3. 3

   LPG Regulator / Vaporizer (EPR) Inspection: Check the Electronic Pressure Regulator for oil separation or 'heavy ends' buildup, which fouls internal components and sensors.

4. 4

   Diaphragm Check: Inspect the diaphragms inside both the LPG regulator and the mixer assembly for cracks, ruptures, or stiffness.

5. 5

   Throttle Body Check: Listen to and observe the throttle body. A failing throttle body may click rapidly or shut on and off erratically.

6. 6

   Vacuum Leak Check: Spray carburetor cleaner around the intake manifold and vacuum lines to check for vacuum leaks, which can skew fuel trim readings.

1. 1

   Clear Airflow Restrictions

   Remove any blockages found in the air intake hoses and replace a heavily soiled air filter.

2. 2

   Service the LPG Regulator

   If the regulator is fouled with oil from bad propane, drain the heavy ends. If the internal diaphragm is cracked or the unit is heavily contaminated, replace the entire LPG Regulator assembly.

3. 3

   Replace Faulty O2 Sensors

   If diagnostic monitoring showed the O2 sensor was unresponsive or out of range, replace the affected Oxygen sensor.

4. 4

   Replace the Mixer Diaphragm

   If the mixer assembly diaphragm is torn, install a replacement diaphragm or replace the mixer assembly.

5. 5

   Replace the Throttle Body

   If the throttle body is mechanically failing or clicking erratically despite a healthy fuel supply, replace it.

6. 6

   Clear Codes and Test

   Use the diagnostic handset to clear the 522660-0 code. Run the forklift under a normal load to ensure it enters closed-loop operation and verify that the code does not return.