MY51 Primera engine light

[SilentDeath]

Now my dads car has gone wrong


Engine light came on a few months ago took it to a garage that charged him £30 to put 2 bottles of fuel system cleaner through it. the light went off and he was happy.
He told my dad the labda sensor was slow and might need replacing if it came back.


Last week the light came back on so he went and put 2 bottles of redex in the tank to no effect but the original garage is too busy to do it for a while. So he has it booked in at the stealership which will probably cost him a good £50 to do nothing (as is usual with dealerships).

We have a spare lamda sensor (from the saab... they are all the same? just wiring/connectors.. 3 wires vs 4.. of which two are sensor & two are heater) so I am tempted to just swap it over and see if it helps.





However what I want to know, will the engine light go out by itself once it is fixed or does it need to be cleared/reset? if so might the fault have only happened once for a split second and then the light stays on for ever? i.e it might be perfectly fine as it is now. atleast with my 16 year old saab the light would flash the code of the fault