Intermittent Engine Cutout

[kiwi12]

My 2001 Toyota Coaster (small bus) has developed a strange problem. The engine runs fine, but will intermittently cut out when either idling or when driving slowly, soon after setting off (before the engine has reached operating temp). Other times it will run fine for a few hundred kms, then it might cut out twice within 2 kms. Usually it will restart OK, but sometimes only after waiting for 10-20 mins.

It was diagnosed as a fault P1215-EDU. One mechanic said the possible fault is in the injection pump spill valve, sometimes at the EDU controller, but I'd like to be sure of this before replacing it for the whopping charge quoted.

Has anyone come across this problem or have any ideas?

Engine is an HBD51, 4.2 Intercooled Turbo Diesel, mileage approx 150,000kms.

Many thanks.