Kohler LH630-775 Service Manual page 71

2. Oxygen Sensor Related
a. Sensor connector or wiring problem.
b. Sensor contaminated or damaged.
c. Exhaust leak.
d. Poor ground path.
e. Pin circuit #20 wiring or connectors.
3. TPS Sensor Related
a. Throttle plate position incorrectly set or
registered during "Initialization.''
b. TPS problem or malfunction.
4. Engine Wiring Harness Related
a. Difference in voltage between sensed voltage
(pin circuit 2) and actual injector voltage
(circuit 45).
5. Systems Related
a. Ignition (spark plug, plug wire, ignition coil.
b. Fuel (fuel type/quality, injector, fuel pump,
fuel pressure.
c. Combustion air (air cleaner dirty/restricted,
intake leak, throttle bores).
d. Base engine problem (rings, valves).
e. Exhaust system leak.
f. Fuel in the crankcase oil.
g. Blocked or restricted fuel return circuit to
tank.
6. ECU Related
a. ECU-to-harness connection problem.
Code: 34
Source: Oxygen Sensor/Fuel System
Components
Explanation: Long term fuel adaptation control is
at the upper or lower limit.
Expected Engine
Response: System operates "closed loop." No
appreciable performance loss as long
as the temporary adaptation can
provide sufficient compensation.
Possible Causes:
1. Oxygen Sensor Related
a. Sensor connector or wiring.
b. Sensor contaminated or damaged.
c. Exhaust leak.
d. Poor ground path.
e. Pin circuit #20 wiring or connectors.
2. TPS Sensor Related
a. Throttle plate position incorrect during
"Initialization" procedure.
b. TPS problem or malfunction.
3. Engine Wiring Harness Related
a. Difference in voltage between sensed voltage
(pin circuit 2) and actual injector voltage
(circuit 45).
b. Problem in wiring harness.
c. ECU-to-harness connection problem.
4. Systems Related
a. Ignition (spark plug, plug wire, ignition coil.
b. Fuel (fuel type/quality, injector, fuel pressure,
fuel pump).
c. Combustion air (air cleaner dirty/restricted,
intake leak, throttle bore).
d. Base engine problem (rings, valves).
e. Exhaust system leak (muffler, flange, oxygen
sensor mounting boss, etc.).
f. Fuel in the crankcase oil.
g. Altitude.
h. Blocked or restricted fuel return circuit to
tank.
Code: 42
Source: Engine (Coolant) Temperature Sensor
Explanation: Not sending proper signal to ECU.
Expected Engine
Response: Engine may be hard to start because
ECU can't determine correct fuel
mixture.
Possible Causes:
1. Temperature Sensor Related
a. Sensor wiring or connection.
2. Engine Wiring Harness Related
a. Pin circuits 4, 6 and/or 4A damaged (wires,
connectors) or routed near noisy signal (coils,
alternator, etc.).
b. ECU-to-harness connection problem.
3. System Related
a. Engine is operating above the 176°C (350°F)
coolant temperature sensor limit.
b. ECU-to-harness connection problem.
Section 5B
EFI Fuel System
5B.31
5B