DTC 25
CODE - 25 AIR/FUEL RATIO LEAN MALFUNCTIONCircuit Description
The main oxygen sensor is located in the exhaust manifold.
It indirectly determines whether the fuel mixture is rich or lean by detecting the concentration of oxygen present in the exhaust gas.
Detecting Condition
1: Only for California specification vehicles.
2: Refer to Trouble Code Descriptions, note *5
Trouble Code Detection Driving Pattern
Purpose of the driving pattern.
(a) To simulate diagnostic trouble code detecting condition after diagnostic trouble code is recorded.
(b) To check that the malfunction is corrected when the repair is completed confirming that diagnostic trouble code is no longer detected.
NOTE: Before this test, check the feedback voltage for oxygen sensor. Component Tests and General Diagnostics
(1) Disconnect the EFI fuse (15 A) for 10 sec. or more, with IG switch OFF. Initiate test mode (Connect terminal TE2 and E1 of data link connector 1 with IG switch OFF).
(2) Start engine and warm up.
(3) After the engine is warmed up, let it race at 2,500 rpm for 3 min.
(4) After performing the racing in step (3), perform idling for 1 min.
NOTE: If a malfunction exists, the Malfunction Indicator Lamp will light up during step (4).
CAUTION: If the conditions in this test are not strictly followed, detection of the malfunction will not be possible.
Diagnostic Chart
Wiring Diagram
Step 1:
Step 2:
Step 3:
Step 4:
Step 5:
Step 6:
Step 7:
Step 8:
Step 9:
Inspection Procedure