NOTE
Be sure the battery is fully charged.

Main Harness [B] Oxygen Sensor [C]
Special Tool - Measuring Adapter: 57001-1700
Oxygen Sensor Heater Power Source Voltage Connections to Adapter: Digital Meter (+) → R (main harness W/R) lead Digital Meter (–) → Frame Ground terminal

Power Source Voltage Standard: Battery Voltage
If the reading is in specification, but the problem still exists, replace the ECU (see ECU Removal/Installation in the Fuel System (DFI) chapter).
If the reading is out of the standard, check the following.
ECU Relay Fuse 15 A (see Fuse Inspection in the Electrical System chapter) Power Source Wiring (see Oxygen Sensor Circuit)
If the fuse and wiring are good, remove the ECU and check the wiring for continuity between harness connectors.
Special Tool - Hand Tester: 57001-1394
Disconnect the ECU and sensor connectors.

Wiring Continuity Inspection ECU Connector [A] ←→ Oxygen Sensor Connectors [B] R lead (ECU terminal 76) [C]
If the wiring is good, check the ECU for its ground and power supply (see ECU Power Supply Inspection in the Fuel System (DFI) chapter).
If the ground and power supply are good, replace the ECU (see ECU Removal/Installation in the Fuel System (DFI) chapter).
Oxygen Sensor Circuit

1. ECU
2. Oxygen Sensor
3. Ignition Switch
4. Joint Connector F
5. Joint Connector A
6. Fuse Box 1
7. Ignition Fuse 15 A
8. Relay Box
9. ECU Main Relay
10. Frame Ground 3
11. Starter Relay
12. ECU Fuse 15 A
13. Main Fuse 30 A
14. Battery
15. Engine Ground
Oxygen Sensor Heater Resistance Inspection
KIBS Hydraulic Unit Communication Error (Service Code 1b, KIBS Equipped
Models)Cleaning Vehicle before Disassembly
Clean the vehicle thoroughly before disassembly. Dirt or
other foreign materials entering into sealed areas during vehicle
disassembly can cause excessive wear and decrease
performance of the vehicle.
Arrangement and Cleaning of Removed Parts
Disassembled parts are easy to confuse. Arrange ...
Check 2-2: Fuel Level Warning Inspection
Remove:
Fuel Tank (see Fuel Tank Removal in the Fuel System
(DFI) chapter)
Connect the resistor(s) [A] (about 50 to 100 Ω) between
the fuel pump connector terminal [B] of the main harness
side and the battery negative (–) terminal [C] as shown.
Turn the ignition switch ...
Valve Removal
Remove the cylinder head (see Cylinder Head Removal).
Remove the valve lifter and shim.
Mark and record the valve lifter and shim locations so they
can be installed in their original positions.
Using the valve spring compressor assembly, remove the
valve.
Special Tools - Valve ...