What Does P06C6 Mean?
The ECM has detected that the glow plug in cylinder 2 is not operating correctly on this diesel engine. The glow plug may be drawing incorrect current, showing abnormal resistance, or failing to heat to the proper temperature. Symptoms include hard cold starts, rough idle during warm-up, white exhaust smoke, and increased cranking time in cold weather.
Common Causes
45%
Failed or degraded glow plug in cylinder 2 (open circuit, high resistance, or carbon fouling)
20%
Wiring harness fault — corroded connector, chafed wire, or broken conductor to cylinder 2
15%
Glow plug control module (GPCM) malfunction not providing correct power to cylinder 2
12%
Poor ground connection at the glow plug or engine ground point
8%
ECM glow plug monitoring circuit internal fault
Diagnostic Steps
1
Disconnect the cylinder 2 glow plug connector and measure plug resistance — expect 0.5–2.0 ohms for a healthy plug. An open reading or greater than 6 ohms means the plug is failed.
2
Check for battery voltage at the cylinder 2 glow plug harness connector while the glow plug preheat cycle is active (key ON, engine cold). Absence of voltage indicates a wiring or GPCM problem.
3
Visually inspect the wiring and connector to cylinder 2 for heat damage, corrosion, or mechanical wear from engine vibration.
4
Use a clamp ammeter to measure current draw during the glow cycle — compare cylinder 2 (expect 15–25A initial, tapering to 8–12A) against adjacent cylinders for consistency.
5
If plug and wiring are within spec, test the GPCM output for cylinder 2 with a multimeter to confirm proper voltage and duty cycle.
Estimated Repair Cost
$75 - $350
Parts + labor, varies by vehicle and location
The ECM has detected that the glow plug in cylinder 2 is not operating correctly on this diesel engine. The glow plug may be drawing incorrect current, showing abnormal resistance, or failing to heat to the proper temperature. Symptoms include hard cold starts, rough idle during warm-up, white exhau...
The most common cause of P06C6 (Cylinder 2 Glow Plug Incorrect) is: Failed or degraded glow plug in cylinder 2 (open circuit, high resistance, or carbon fouling)
Typical repair costs for P06C6 range from $75 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive in warm conditions, but cold starting will be compromised. Two or more failed glow plugs can make the engine impossible to start in freezing temperatures. Extended cranking stresses the starter motor and battery. Continued driving with poor combustion during warm-up can cause cylinder wall washing and premature wear.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P06C6 to identify the root cause.
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Quick Info
Category
Powertrain
System
Diesel Cold Start / Glow Plug System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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