redlig
Member
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- 3,914
- Location
- wiltshire uk
Well I never . We live and learn.Of course.
An example from today - DTC set of 'long term SCR efficiency exceeded' no other fault codes, engine and SCR system test OK. NOx sensor values OK on test drive, DEF metering valve port very clean but DEF pressure and delivery volume test results within limits. Actual cause was one of the exhaust temperature sensors upstream of the catalytic converter reading low.
Example from a few years ago - petrol engine with 'conventional' ignition distributor, runs fine at tickover, accelerates OK, but misfires on deceleration, already had new points & condenser fitted - checked gap - OK, no track marks on dist. cap, vacuum advance working OK, ballast resistor on coil tests OK. Actual cause was fixed contact had fallen off old set of points and jammed up the centrifugal advance in the distributor, igniton had been re-timed at the same time as points & condenser replaced.
So yes, knowledge, understanding and an appreciation of actual values is needed to diagnose vehicle faults, whatever the age of the vehicle.