P0338 - GLOW PLUGS/HEATER “A” CIRCUIT MALFUNCTION

 

DTC Code P0338 General Description

The electric plug spark plugs are designed to heat up the combustion chamber, making it easier to start the engine at low temperatures.

These plugs get hot before and during start-up. Afterwards, they remain open to avoid engine failure until the ideal temperature for good performance is reached. This process reduces pollutant gas emissions and smoke levels when the engine is cold.

The engine control module (ECM) controls the heater plug by monitoring the coolant temperature and heater plug voltage. The heater system has eight separate power circuits between the controller and the heater plug. If the feedback voltage from the controller to the engine control module (ECM) is out of range, DTC code P0338 is set.

Fault code P0338 General symptoms

Check that the engine indicator light is illuminated.

The engine is difficult to start, especially at low temperatures.

Causes for OBD2 code P0338 General

Code P0338 may be caused by one or more of the following problems:

• There may be a short in the glow plug wiring.
  
  
• The glow plugs may be faulty.
  
  
• The fuse is shorted.
  
  
• The glow plug relay may be faulty.
  
  
• Possible solutions for code DTC P0338 General

To resolve code DTC P0338, you can check the following components:

• Replace the appropriate fuse, if it is blown, replace it.
  
  
• Visually inspect the glow plugs, their cables and associated connectors for oxidation, loose screws or burned out cables.
  Repair or replace if necessary.
  
  
• Using a digital multimeter, check that the cable connectors meet the manufacturer's specifications.
  
  
• Disconnect the wires from the glow plugs, measure the resistance, and compare it to the manufacturer's specifications.
  
  
• If you are replacing the glow plug, check the condition of the glow plug first. To do this, remove the threads like a regular spark plug and check its operation by applying 12 volts to the terminals for 3 seconds without grounding. If it glows red, then everything is fine. Conversely, if it's opaque red, it's a defect.