Peugeot 206 1.4 losing pulse to injector(s)?

My mechanic has just phoned me and told me my car is misfiring. He said they'd checked the cylinders and they're all receiving the correct compression and all the cylinders are sparking. but my car is losing pulse to one or more of the injectors (I'm pretty sure they said one.) They've told me an Auto Electrician needs to test it to determine if it's a problem with the wiring or the ECU. are there any other problems that could point to it being a wiring problem? and how much could this potentially cost me!?!?!?!?!