Circuit Description
WARNING: This page is about a different car, the 1995 Lexus LS 400. However, it is still accessible from the selected car via links, so may be relevant.
The EGR system recirculates exhaust gas through intake system to reduce combustion temperature and NOx emissions. The amount of EGR valve opening is controlled by a step motor located inside of EGR valve. The ECM operates the step motor in response to engine operating conditions. The EGR valve is closed under the following conditions:
- Coolant temperature below 129°F (54°C).
- Vehicle under deceleration.
- Light engine load.
- Engine speed more than 4000 RPM.
- Engine idling.
- Park/neutral position switch on.
Code is set when EGR gas temperature sensor value is high during EGR cut-off when engine is cold, or if EGR valve is always open. Possible causes are:
- EGR valve stuck open.
- EGR step motor circuit.
- EGR gas temperature sensor short circuit.
- ECM malfunction.