C5 2001 2.2HDi - Fault code P0402 EGR – problem solved – melted and blocked vacuum pipe

[aspire_helen]

For several months the car has appeared occasionally sluggish with reduced mpg, but no diagnostics warning. First, a hot front wheel evidenced that the hand brake lever on the brake caliper had seized and was binding. Caliper replaced. A few weeks later…seemed sluggish again. This time the other front wheel was hot, evidencing a partially seized caliper. Caliper replaced (although I think a piston replacement would have done). A few weeks later the sluggishness became apparent again. I eventually plugged in Lexia which returned P0402 EGR flow excessive. As the EGR valve has had no attention over its 25year/200K+ miles life, I anticipated replacing the EGR valve.
However, a quick examination of the vacuum pipe revealed a likely cause. My attention was attracted by a hole abraded in the heat sheathing (white) covering a section of rigid plastic vacuum pipe (black) just a few inches short of the EGR valve. I removed the sheathing expecting to find a hole worn in the vacuum pipe itself. But no. Under the heat sheathing, a 6inch section of the rigid plastic pipe had melted, or more exactly it had been softened by heat and the vacuum had then “sucked” it flat; so the pipe was blocked. In essence, the protective sheathing had not stopped the vacuum hose from melting, but had in fact hidden it!
I could detect no unusual source of the heat (eg exhaust gas leak), nor other signs of plastic melting in the vicinity, other than perhaps the vacuum pipe had perhaps been too close to the EGR outlet pipe. The car appears to drive OK….fingers crossed!!

[mickthemaverick]

Nice one Peter, well found and probably a useful tip for others with EGR trouble