P0382

P0382 is platform-dependent — on many domestic light-truck and passenger applications it sets as 'Exhaust Gas Recirculation Sensor B Circuit' (a secondary EGR position or pressure feedback fault), while on diesel platforms it commonly latches as 'Glow Plug B Malfunction' indicating the secondary glow-plug bank or a specific plug in a multi-channel glow-plug control module has failed its current-monitor check. Cheapest-first ladder, diesel context: (1) at key-on with engine cold (coolant below 50 F), watch glow-plug system current on the scan tool — total system current should jump to roughly 7-20 A per plug during the initial 5-30 second wait-to-start phase, then taper as plug resistance climbs with temperature; a bank that draws zero or that pulls 2x normal indicates an open or shorted plug. (2) Disconnect each glow plug at the bus bar and measure resistance pin-to-ground individually — a healthy plug reads 0.4 to 2.0 ohms cold; an open plug reads infinity, a shorted plug reads under 0.2 ohms. (3) Backprobe the glow-plug control module (GPCM) output for the affected bank and verify PWM duty cycle commands 0-100% in response to coolant temperature; a stuck-off output with all plugs good points to the module, a stuck-on output points to a shorted driver. Expensive-misdiagnosis caveat: before replacing the glow-plug control module, check the glow plug RESISTANCE individually — a single shorted plug pulls the control module current high and sets P0382, but the module is fine; replacing the module without fixing the shorted plug just kills the new module on the first cold start.

Vehicle-specific patterns: 2003-2007 Ford 6.0L Powerstroke is the canonical P0382 ticket — the GPCM mounts on the passenger-side valve cover, sees direct heat soak, and fails repeatedly; Ford TSB guidance is to verify all eight plugs ohm out before reinstalling a new module. 2008-2010 Ford 6.4L Powerstroke throws P0382 from individual plug failures more often than module failures, but the failure mode that kills GPCMs is a single shorted plug taking the module with it. 2001-2010 GM Duramax LB7-LMM mounts the glow-plug controller on the side of the engine block and throws P0382 when the controller's internal solder joints crack from thermal cycling. 2007-2018 RAM Cummins 6.7L places glow plugs directly in the cylinder head (rather than a grid heater intake) and throws P0382 from individual plug failures; the cheaper fix is per-plug rather than full module. Estimated repair: $80 (single plug) to $950 (controller + multiple plugs).