LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Suzuki >> 2006 >> Aerio Premium, FWD, Standard >> Repair and Diagnosis (Single Page) >> Engine Performance >> Engine Control Systems >> Engine General Information And Diagnosis >> Diagnostic Information and Procedures >> DTC P0125: Insufficient Coolant Temperature for Closed Loop Fuel Control >> DTC Troubleshooting
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC Troubleshooting

DIAGNOSIS PROCEDURE

Step Action YES NO
1  Was "Engine and Emission Control System Check" performed?  Go to Step 2. Go to ENGINE AND EMISSION CONTROL SYSTEM CHECK .
2  Engine coolant temp. check 
  1. Connect scan tool to DLC with ignition switch turned OFF.
  2. Start engine and warm up to normal operating temperature with idling.
  3. Check engine coolant temp. using scan tool.

Is engine coolant temp. less than 20°C (68°F)? 		 Go to Step 3. Go to Step 10.
3  Check ECT voltage 
  1. Disconnect connector from ECT sensor with ignition switch turned OFF.
  2. Check for proper connection to ECT sensor connector at "LT GRN" and "ORN" wire terminals.
  3. If OK, then turned ON ignition switch, check voltage between "LT GRN" wire terminal of ECT sensor connector and vehicle body ground.
G04589454

 
Is voltage about 4 - 6 V at each terminal? 		 Go to Step 6. Go to Step 4.
4  Check ECM voltage 
  1. Disconnect connectors from ECM with ignition switch turned OFF.
  2. Remove ECM from vehicle body and connect connectors to ECM.
  3. Check for proper connection of ECM connector at "C46-12" terminal.
  4. If OK, then turn ON ignition switch, check voltage between "C46-12" terminal of ECM connector and vehicle body ground.

Is voltage about 4 - 6 V at each terminal? 		 Open wire in "LT GRN" circuit.
If wire and connection are OK, go to Step 5.		 Go to Step 5.
5  Check ECM sensor harness voltage 
  1. Disconnect connectors from ECM with ignition switch turned OFF.
  2. Turn ON ignition switch.
  3. Check voltage between "LT GRN" wire terminal of ECT sensor connector and vehicle body ground.

Is voltage about 0 V at each terminal? 		 Go to Step 6. "LT GRN" wire shorted to other circuits.
If wire are OK, substitute a known-good ECM and recheck.
6  Check ECT sensor harness resistance 
  1. Measure resistance between "C46-12" terminal of ECM connector and "LT GRN" wire terminal of ECT sensor connector with ignition switch turn OFF.

Is resistance below 5 ohm? 		 Go to Step 7. High resistance wire in "LT GRN" circuit.
7  Check ECT sensor ground circuit 
  1. Connect connectors to ECM.
  2. Measure resistance between "ORN" wire terminal of ECT sensor connector and vehicle body ground.

Is resistance below 10 ohm? 		 Go to Step 9. Go to Step 8.
8  Check ECT sensor ground circuit 
  1. Measure resistance between "C46-16" terminal of ECM connector and vehicle body ground.

Is resistance below 5 ohm? 		 Open or high resistance wire in "ORN" circuit.
Poor "C46-16" connection.		 Open or high resistance wire in "C45-6" and/or "C46-6" circuit.
If circuit are OK, substitute a known-good ECM and recheck.
9  Check ECT sensor 
  1. Check ECT sensor according to Engine Coolant Temperature (ECT) Sensor Inspection  .

Is it good condition? 		 Go to Step 10. Replace ECT sensor.
10  Thermostat check 
  1. Check thermostat referring to THERMOSTAT INSPECTION .

Is thermostat in good condition? 		 Substitute a known-good ECM and recheck. Replace thermostat.
scientia non olet · About LEMON Manuals