6.8 - Exhaust Gas Recirculation System ( ,  )

This aims to reduce emissions by reducing combustion temperatures in the cylinders. This is done by recirculating exhaust gasses back into the inlet manifold under certain engine conditions, typically part throttle operation, as determined by the ECU.

The EGR pipework leads from the exhaust side, under the exhaust manifold, around to the inlet manifold. On most models, the electrically operated valve is located on the inlet side, but on XJR models it is mounted adjacent to the exhaust manifold itself.

An intake temperature sensor on the intake side near the EGR inlet can detect the correct operation of the system and will set an error code in the ECU if this does not occur. Common causes are failure of the valve itself, or the pipework becoming blocked, particularly at the entry into the inlet manifold.

There has been a recall on '95 - '97 models to overcome blockages by forcing the ECU to periodically operate the valve. However, this has itself caused problems with '95 models and a second recall is being introduced.