We've just had a Ford KA serviced which was returned with the oil warning light illuminated. The car was returned to the garage who say a new HEGO sensor is required. Can you tell me what this sensor does and can it cause firstly the oil lamp to come on or what light will come on.

Thanks in advance

steve, August 2010

Thanks Nigel.
After I wrote the question doubt came to mind so I checked what my wife had told me and it was the engine management light that had lit not the oil light.
Is is possible for the Lambda sensor to be damaged whilst the car is being serviced?

Steve, August 2010

The Lambda sensor measures the oxygen/fuel mix levels in the exhaust system and based on this information the engine ECU adjusts the fuel injectors and spark timing to ensure the best combustion in the engine and so reduce the amount of emmissions out of the exhaust system. It has nothing to do with the oil light, that is a warning of low oil pressure inside the engine, and low oil pressure means possible damage to the components inside the engine!!.
If the Lambda sensor failsit will normally put on the "Check Engine" warning light normally an engine shaped light with a lightning flash though it, or on some earlier Ka's it was a symbol like an exhaust silencer box with wavvy lines above the box.

nigel, August 2010