EG–428 ENGINE – 2JZ–GE ENGINE TROUBLESHOOTING DTC 25 26 Air–Fuel Ratio Lean Rich Malfunction CIRCUIT DESCRIPTION See page EG–419 for the circuit description DTC No. | Diagnostic Trouble Code Detecting Condition | Trouble Area (1) (Main heated*1) oxygen sensor voltage is 0.45 V or less (lean) for 90 sec. under codi– tions (a) and (b): (2 trip detection logic)*2 (a) Engine coolant temp.: 70°C (158°F) or more (b) Engine speed: 1,500 rpm or more • Open or short in (main heated*1) oxygen sensor circuit • (Main heated*1) oxygen sensor • Ignition system • ECM (2)*1 Difference of air–fuel ratio feedback compensation value between front (No. 1 ~ 3 cylinders) and rear (No. 4 ~ 6 cylinders) is more than 15 percentage for 20 sec. or more under conditions (a) and (b): (2 trip detection logic)*2 (a) Engine speed: 2,000 rpm or more (b) Engine coolant temp.: Between 60°C (140°F) and 95°C (203°F) • Open and short in injector circuit • Fuel line pressure (injector leak, blockage) • Mechanical system malfunction (skipping teeth of timing belt) • Ignition system • Compression pressure (foreign object caught in valve) • Volume air flow meter (air intake) • ECM 25 (3)*1 Engine speed varies by more than 15 rpm over the preceding crank angle period during a period of 20 sec. or more under conditions (a) and (b): (2 trip detection logic)*2 (a) Engine speed: Idling (b) Engine coolant temp.: Between 60°C (140°F) and 95°C (203°F) • Open and short in injector circuit • Fuel line pressure (injector leak, blockage) • Mechanical system malfunction (skipping teeth of timing belt) • Ignition system • Compression pressure (foreign object caught in valve) • Volume air flow meter (air intake) • ECM (1)*1 Difference of air–fuel ratio feedback compensation value between front (No. 1 ~ 3 cylinders) and rear (No. 4 ~ 6 cylinders) is more than 15 percentage for 20 sec. or more under conditions (a) and (b): (2 trip detection logic)*2 (a) Engine speed: 2,000 rpm or more (b) Engine coolant temp.: Between 60°C (140°F) and 95°C (203°F) • Open and short in injector circuit • Fuel line pressure (injector leak, blockage) • Mechanical system malfunction (skipping teeth of timing belt) • Ignition system • Compression pressure (foreign object caught in valve) • Volume air flow meter (air intake) • ECM 26 (2) Engine speed varies by more than 15 rpm over the preceding crank angle period during a period of 20 sec. or more under conditions (a) and (b): (2 trip detection logic)*2 (a) Engine speed: Idling (b) Engine coolant temp.: Between 60°C (140°F) and 95°C (203°F) • Open and short in injector circuit • Fuel line pressure (injector leak, blockage) • Mechanical system malfunction (skipping teeth of timing belt) • Ignition system • Compression pressure (foreign object caught in valve) • Volume air flow meter (air intake) • ECM *1: Only for California specification vehicles *2: See page EG–397.