P0675
UniversalCylinder 5 Glow Plug Circuit Malfunction
Medium SeverityThis code indicates an electrical issue within the circuit of the Cylinder 5 Glow Plug. A malfunction here typically means the glow plug is not heating correctly, which can lead to difficulty starting the engine, especially in cold weather, and rough idling.
⚠️ Before You Begin (Safety First)
Always disconnect the battery before attempting any electrical repairs. Allow the engine to cool completely before working on glow plugs, as they can be extremely hot and can cause severe burns. Use proper eye protection and gloves.
Common Symptoms
- Check Engine Light illuminated
- Difficulty starting the engine in cold weather
- Rough idling during initial startup
- Increased exhaust smoke during startup
- Engine misfires during warm-up
Common Causes
- Faulty or burned out Cylinder 5 Glow Plug
- Open or short in the Cylinder 5 Glow Plug wiring circuit
- Malfunctioning Glow Plug Control Module (GPCM) or relay
- Corroded or loose electrical connections at the glow plug or GPCM
Frequently reported on: Ford F-250/F-350 (2003-2010 Power Stroke), Chevrolet Silverado/GMC Sierra 2500/3500 (2001-2010 Duramax), Ram 2500/3500 (2007-2012 Cummins), Volkswagen Jetta TDI (2004-2015), Mercedes-Benz Sprinter (2007-2018)
Diagnostic Steps
- Visually inspect the wiring and connector for the Cylinder 5 Glow Plug for any damage or corrosion.
- Using a multimeter, test the resistance of the Cylinder 5 Glow Plug; a reading significantly different from the others or an open circuit indicates a faulty plug.
- Check for voltage at the Cylinder 5 Glow Plug connector during the pre-heat cycle to ensure the Glow Plug Control Module is supplying power.
- If the glow plug is confirmed faulty, carefully remove and replace it with a new one, ensuring proper torque specifications are met to prevent damage.
👨🔧 When to Call a Professional
If diagnostic steps confirm a faulty glow plug but it appears seized or if you lack the specialized tools for careful removal, it is highly recommended to seek professional assistance. Improper removal can lead to breakage, requiring costly cylinder head removal.
Commonly Asked Questions
What is a glow plug and what does it do?
A glow plug is an electrical heating device used in diesel engines to aid in starting by preheating the combustion chamber, especially in cold weather. This helps ignite the diesel fuel more efficiently.
Can I drive my vehicle with a P0675 code?
While you can typically drive with a P0675 code, you may experience hard starting, rough idling, or increased smoke, particularly in cold conditions. Prolonged driving with a faulty glow plug can impact fuel efficiency and increase emissions.
How do I test a glow plug for fault?
You can test a glow plug using a multimeter. Disconnect the glow plug wire and measure the resistance between the glow plug terminal and a good engine ground. A good glow plug will typically have very low resistance (around 0.6-2 ohms). An open circuit (infinite resistance) indicates a faulty plug.
Why is replacing a glow plug sometimes difficult?
Glow plugs can seize in the cylinder head over time due to carbon buildup or corrosion. Attempting to force a seized glow plug can cause it to break off in the head, leading to a much more complex and expensive repair.
Could something else besides the glow plug cause this code?
Yes, beyond the glow plug itself, issues with the wiring harness to cylinder 5, including breaks or shorts, or a fault within the Glow Plug Control Module (GPCM) or its relay, can also trigger a P0675 code.