1999 PEUGEOT 406 COUPÉ 3.0 V6
With the rear brakes finally sorted, I’ve been able to begin diagnosing the 406’s throttle issues. Often, I’d be driving along and the engine would simply start revving between 2000- 3000rpm of its own accord. After a few seconds, it would slowly reduce to an idle of about 750rpm. Worse still, the power would cut out when stopped at a junction and then it would refuse to re-start, causing an embarrassing traffic jam behind me.
Thankfully Papa Sadlier had a brainwave. A bit of research suggested that the ECU was receiving erroneous information from one or more of the engine sensors. Having seen this issue before, a simple crankshaft sensor replacement usually corrected the problem at a stroke.
Unsure where to find it within the V6 engine bay, I contacted the Peugeot 406 Coupé Owners’ Club, who revealed that it’s located near to the top of the gearbox bell housing where it is bolted to the engine and takes information from the flywheel. Unfortunately this meant that it was buried beneath numerous ancillaries, the cooling system pipework and various electronic systems.
With the bonnet up and the 406 on axle stands, we removed the air filter box, throttle housing and the cross brace from the top of the suspension struts to gain access. Cooling system hoses and electrical wiring were removed to gain access to the confined area where the offending crankshaft sensor was located. Thankfully a recent purchase of 100mm long magnetic sockets came in very useful to remove the 10mm bolt securing the sensor. It was initially exceptionally resistant to being removed from its position where it had sat for 22 years but eventually came free with a liberal soaking in WD40 and some hefty fiddling.
As always, connecting the new part on a 406 has proved to be the easier step in our repair journey. The fitting of the sensor and connecting the electrical sensors was relatively straightforward. The lengthier job was the re-connecting and re-fitting of the hoses, pipes, and wiring that we had removed to actually access it. Remembering where everything should go was a major task in itself!
With the inlet manifold re-fitted with a new gasket seal, we could then ensure that the throttle housing was put back as it was before. The cooling system was then re-filled and any air locks bled. With the cross brace re-fitted to the suspension mounts, it was time for the moment of truth.
As we started the engine it sat hap
