What Does P067A Mean?
The PCM has detected that the glow plug control circuit for cylinder 4 is reading lower voltage than expected. Glow plugs are critical for cold-start ignition in diesel engines, heating the combustion chamber air. The driver may notice hard starting in cold weather, white smoke on startup, or rough idle when the engine is cold.
Common Causes
40%
Failed cylinder 4 glow plug (internal short to ground)
25%
Short to ground in glow plug wiring harness
20%
Faulty glow plug control module (GPCM) output driver
10%
Corroded or damaged connector at glow plug or GPCM
5%
PCM internal fault on glow plug control circuit
Diagnostic Steps
1
Measure the resistance of the cylinder 4 glow plug using a multimeter; typical spec is 0.5-2.0 ohms depending on the manufacturer. A reading near 0 ohms indicates an internal short.
2
Disconnect the glow plug and measure the circuit wiring from the GPCM connector to the glow plug connector for shorts to ground; resistance to ground should be greater than 10k ohms.
3
Inspect the wiring harness from the glow plug control module to cylinder 4 for chafing, heat damage, or pinched wires against the engine block.
4
With the glow plug disconnected, command the GPCM to energize cylinder 4 and measure voltage output at the GPCM connector; it should read battery voltage (12-14V).
5
Compare cylinder 4 glow plug resistance to the other cylinders to identify if it is out of spec relative to its neighbors.
Estimated Repair Cost
$50 - $350
Parts + labor, varies by vehicle and location
The PCM has detected that the glow plug control circuit for cylinder 4 is reading lower voltage than expected. Glow plugs are critical for cold-start ignition in diesel engines, heating the combustion chamber air. The driver may notice hard starting in cold weather, white smoke on startup, or rough ...
The most common cause of P067A (Cylinder 4 Glow Plug Control Circuit Low) is: Failed cylinder 4 glow plug (internal short to ground)
Typical repair costs for P067A range from $50 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The vehicle is generally safe to drive once started. However, cold starting may be significantly more difficult, and prolonged cranking can stress the starter and battery. Extended cold running with incomplete combustion increases emissions and can cause cylinder wash, diluting engine oil.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P067A to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Powertrain
System
Diesel Cold Start / Glow Plug System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
