S-Max 2008. Engine malfunction warning, though car seems fine

[Daksol]

Ford S-Max petrol 2 litre from 2008, very reliable nearly 200,000 km.

For last two years an engine malfunction warning comes up every time the car is started. Apparently competent local workshop cannot see why. Car seems to run fine.

Just bought a bluetooth ODB2 unit linked to Torque Pro app on mobile. That works fine, green lights on connecting to ECU etc. When I take the Faults option it comes back to say none found.

Any ideas on why? Else is there any credible risk running like this? If it were not for the warning I would not think I had a problem.

Thanks.

[Tdci-Peter]

14 hours ago, Daksol said:

Bluetooth ODB2 unit linked to Torque Pro app on mobile. That works fine, green lights on connecting to ECU etc. When I take the Faults option it comes back to say none found.

OBD2 is an international standard for diagnostics, it includes a number of standardised DTCs (error codes). But these codes are much too limited to cover all systems, and all manufacturers use a large number of non-standard DTCs in addition. Universal OBD2 readers may not find these codes.

Forscan is a Ford specific diagnostic system that only costs about £16 for the ELM327 adapter if you have a Windows laptop, or a little more for Android or iOS apps. It can find just about all Ford codes, and there has to be one somewhere in the system if the light is on.

The fault you have seems to be unimportant if has had no effect for two years, but more of a problem is that with the light on all the time, you have no indication if another, more serious fault should happen.

 

[Daksol]

Thanks I will pursue the option you suggest.

[Tdci-Peter]

14 hours ago, Daksol said:

an engine malfunction warning comes up every time the car is started.

Hard to say what that might be. If it was EGR valve (if it has one), then I would expect an OBD2 reader to pick up this code. An O2 sensor could do it, but would also normally show up on OBD2, and be an MoT fail.

On most petrol engines there is some sort of variable vane or valve in the intake manifold. A stuck or broken actuator for this might give a non-standard DTC on every start. It only has a minor effect on emissions or power or economy so would not be obvious when driving the car.

For a bit more on Forscan see: