Citroen with a engine light on,
A scan revealed P1471 EGR motorised throttle unit, Checking the wiring diagram showed a couple of options into what part this could be, So to double check we started unplugging parts on the EGR system, Unplugging the butterfly in the boost pipe threw another code relating to the EGR throttle unit so we now had narrowed down which part is was – now to start testing.
Checking the wring diagram showed that this part was called a intercooler bypass flap (But this car it didn’t bypass the intercooler but the wire numbers matched perfectly)
Wire 1 had 5 volts (Feedback circuit power)
Wire 4 had Battery voltage (Motor Power feed)
Wire 5 had Earth (Feedback circuit earth)
Wire 6 had 1.2Volts (Feedback circuit) using my hand to shut the flap changed this to 4 volts
Now wire 3 had nothing (Even with output testing the butterfly flap)
Next stage was to check for output at the ECU – we found the wire and carrying out output showed we had an earth feed!
A continuity test showed we didn’t have continuity – now to try and find the broken wire
I always start with which part of the loom moves – Between gearbox and body on this Citroen – this part did look OK but while looking we spotted a wire that looked broken sticking out the loom!
We checked and this was the broken wire, Wire repaired and all taped back up the code cleared and engine light went off.