engine will only rev to 2800rpm cooling fan on constantly

citroen c3 desire .
engine will only rev to@2800rpm&cooling fan on consistantly.whilst plugging/unplugging wiring plugs for hundredth time both faults simultaneously disappeared,but after engine turned off for 20mins on restarting back to stage one.
2 garages have diagnosed different problems from fuse board to ecu to throttle body(fault still there.)
could it be the throttle pedal potentiometer?
am really running out of options/ideas & getting expensive.
any practical suggestions would be appreciated,
regards,
Tony

driverpro57 wrote: ↑Sun Feb 13, 2022 4:32 pm 2 garages have diagnosed different problems from fuse board to ecu to throttle body(fault still there.)
could it be the throttle pedal potentiometer?

The engine ECU, the throttle body and the throttle pedal are very reliable.

Do you have the engine light on?

Do you have the temperature light on?

If the fault went away after fiddling with the wiring and connectors, I recommend disconnecting and inspecting the green coolant temp sensor connector and inspecting it for corrosion or damage. Follow the wiring back to the engine ECU looking for chafed or damaged wiring. Disconnect the 3 connectors of the engine ECU and inspect for damage/corrosion.
There is also a 'blue' connector under the thermostat housing. Inspect that too. Ensure the connector is snug and the single wire is sound.


Failing that, I would change the green coolant temp sensor on the thermostat housing.

This is the 'blue' sensor under the thermostat housing. I am not sure but my theory is that the engine ECU is detecting an engine over temp and going int "limp" mode. Again just a theory, if my car was running at the moment I would test it.
Your BIO is a bit misleading and I don't know if your car is a facelift or pre-facelift version. I'm assuming it's a facelift version because you did not mention the temp bars.
The "over temp" light on the face lift version seems to work a little differently to the temp bars on the pre-facelift version and I do not have access to the facelift owners manual.
I am trying to make a connection between the thermo fan running all the time and the throttle limiting.