Engine

P0382 — Glow Plug Circuit "B" Malfunction

Severity: medium Drive with care, to a shop

What P0382 means

The engine control module powers the diesel glow plugs to heat the combustion chambers for cold starts, and it monitors the circuit's current or voltage. P0382 is set when circuit "B" does not behave as expected, such as an open circuit, high resistance or no supply. Typical culprits are failed glow plugs, a bad relay, a blown fuse or wiring problems.

Symptoms

  • Hard or prolonged starting, especially when cold
  • Check engine or glow plug indicator lit
  • Rough idle until the engine warms up
  • White smoke on cold start
  • Extra strain on the battery and starter during starting

Possible causes

  1. Open circuit or high resistance in the circuit "B" wiring
  2. Failed glow plug heating element(s)
  3. Faulty glow plug relay or control module
  4. Blown glow plug fuse
  5. Corroded or loose connectors and terminals
  6. Internal driver failure in the engine computer (rare)

How to diagnose

  1. Scan for codes and freeze frame data, and note any other DTCs
  2. Inspect the glow plug fuse and relay
  3. Inspect glow plug wiring and connectors for damage and corrosion
  4. Measure each glow plug's resistance and compare to spec
  5. Check for power and ground at the relay and plugs with the ignition on
  6. Verify the control signal from the ECM to the relay or glow plug module
  7. Test voltage drop on the power circuit under load

Common fixes

  • Replace failed glow plugs, preferably as a set
  • Replace the glow plug relay or control module
  • Replace the blown fuse after finding the cause of the overload
  • Repair the wiring harness and clean or replace connectors

Questions and answers

Can I drive with a P0382 code?

Usually yes, especially in warm weather. In the cold, though, the engine may not start, and repeated cranking will wear the battery and starter.

What most often causes P0382?

Most often it's burnt-out glow plugs, broken wiring or a bad relay. Start by checking the fuse and measuring each plug's resistance.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.