GEMS Lambda / Oxygen Sensor - Pre Catalyst

Product information

A single lambda sensor (sometimes referred to as an O2 or oxygen sensor), suitable for Rover V8 engines which are fitted with the GEMS injection system, as used in P38 Range Rovers between 1994 and 1994, Defender 90 50th Anniversary editions, some Morgan and TVR models and NAS spec Discovery 1's. The GEMS injection system can be identified by its square intake and coil packs, which are 4 coils, each with 2 posts, mounted to a long bracket behind the intake plenum. The ECU is a silver box with 2 black plugs and one red plug. The listing here is for the pre-cat lambda sensor, which we recommend is fitted on all vehicles even if catalysts are not being used. Please note that there are two variants of the GEMS lambda sensor, the easiest way to tell them apart is by the colour of the plug, which will be either black or grey. We can supply both variants, so please choose the item you require using the drop down menu above.

RPi Advice

  • The best way of testing your lambda sensor is using a diagnostics machine which can show you the live data reading from the sensor. If the reading is "switching" (ie raising and falling) whilst the engine is idling, this indicates the sensors are likely to be reading. If you don't currently have diagnostics, Hawkeye comes highly recommended and will be worth its weight in gold for many Rover V8 owners.
  • Functional lambda sensors are essential to correct part-throttle operation of the GEMS management system
  • Lambda sensors should still be fitted on vehicles without catalysts, but make sure chip the ECU appropriately to account for the extra airflow or risk running your engine lean.
  • Be careful not the cross the wires between banks - we've seen this done and it causes one bank to run extremely lean whilst the other runs extremely rich.

Weight 0.75kg