EFI SYSTEM-BOSCH
86
24 690 01 Rev. KKohlerEngines.com
Code 33
Component: Oxygen Sensor/Fuel System
Fault: System too rich. Temporary fuel
adaptation control is at upper limit.
Condition: Fuel Supply Related (nothing lean–only
rich)
● Restricted return line causing
excessive fuel pressure.
● Fuel inlet screen plugged (in-tank fuel
pump only).
● Incorrect fuel pressure at fuel rail.
Oxygen Sensor Related
● Sensor connector or wiring problem.
● Sensor contaminated or damaged.
● Exhaust leak.
● Poor ground path.
● Pin circuit wiring or connectors.
Pin 10 for “35 Pin” (MA 1.7)
Metal-Cased ECU.
Pin 11 for “24 Pin” (MSE 1.0)
Plastic-Cased ECU.
Pin 20 for “32 Pin” (MSE 1.1)
Plastic-Cased ECU.
TPS Sensor Related
● Throttle plate position incorrectly set or
registered during Initialization.
● TPS problem or malfunction.
Engine Wiring Harness Related
● Difference in voltage between sensed
voltage (pin circuit 17 for metal-cased
ECU, pin circuit 2 for plastic-cased
ECU) and actual injector voltage
(circuit 45/45A).
Systems Related
● Ignition (spark plug, plug wire, ignition
coil.
● Fuel (fuel type/quality, injector, fuel
pump, fuel pressure.
● Combustion air (air cleaner dirty/
restricted, intake leak, throttle bores).
● Base engine problem (rings, valves).
● Exhaust system leak.
● Fuel in crankcase oil.
● Blocked or restricted fuel return circuit
to tank.
ECU/Harness Related
● ECU-to-harness connection problem.
Code 34
Component: Oxygen Sensor/Fuel System
Components
Fault: Long term fuel adaptation control is at
upper or lower limit.
Condition: System operates closed loop. No
appreciable performance loss as long
as temporary adaptation can provide
suffi cient compensation.
Conclusion: Oxygen Sensor Related
● Sensor connector or wiring problem.
● Sensor contaminated or damaged.
● Exhaust leak.
● Poor ground path.
● Pin circuit wiring or connectors.
Pin 10 for “35 Pin” (MA 1.7)
Metal-Cased ECU.
Pin 11 for “24 Pin” (MSE 1.0)
Plastic-Cased ECU.
Pin 20 for “32 Pin” (MSE 1.1)
Plastic-Cased ECU.
TPS Sensor Related
● Throttle plate position incorrect during
Initialization procedure.
● TPS problem or malfunction.
Engine Wiring Harness Related
● Difference in voltage between sensed
voltage (pin circuit 17 for metal-cased
ECU, pin circuit 2 for plastic-cased
ECU) and actual injector voltage
(circuit 45/45A).
● Problem in wiring harness.
● ECU-to-harness connection problem.
Systems Related
● Ignition (spark plug, plug wire, ignition
coil.
● Fuel (fuel type/quality, injector, fuel
pressure, fuel pump).
● Combustion air (air cleaner dirty/
restricted, intake leak, throttle bores).
● Base engine problem (rings, valves).
● Exhaust system leak (muffl er, fl ange,
oxygen sensor mounting boss, etc.).
● Fuel in crankcase oil.
● Altitude.
● Blocked or restricted fuel return circuit
to tank.
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