What Does P037F Mean?
The glow plug sense circuit is reporting a higher-than-expected voltage, suggesting the sense line may be open or disconnected, or a glow plug has failed open-circuit preventing current flow through the sense path. This diesel engine code means the glow plug control module cannot verify proper glow plug operation. Symptoms include hard cold starting, rough idle when cold, and white smoke from unburned fuel.
Common Causes
35%
Open-circuit glow plug with a burned-out heating element
25%
Broken or disconnected sense wire between the glow plug control module and glow plug
15%
Corroded or backed-out pin in the glow plug control module connector
15%
High-resistance connection at the glow plug bus bar terminal
10%
Glow plug control module internal high-side driver failure
Diagnostic Steps
1
Check glow plug control module PIDs to identify which cylinder's sense circuit is reading high. This narrows diagnosis to a specific plug and wire.
2
Remove the glow plug bus bar and measure each plug resistance from terminal to ground. An open-circuit (OL) reading confirms a burned-out plug. Good plugs read 0.5-2.0 ohms.
3
With the bus bar disconnected, measure continuity of the sense wire from the GPCM connector to each glow plug terminal. An open reading indicates a broken wire or disconnected terminal.
4
Inspect the glow plug bus bar mounting nuts for corrosion or looseness. Clean the terminals and torque the nuts to manufacturer specification (typically 10-15 Nm). A loose connection creates high resistance that reads as an open on the sense circuit.
5
If plugs and wiring test good, use a known-good glow plug as a test load on the suspect circuit. Command the GPCM to activate the circuit and verify the sense reading returns to normal. If not, the GPCM sense input is faulty.
Estimated Repair Cost
$60 - $500
Parts + labor, varies by vehicle and location
The glow plug sense circuit is reporting a higher-than-expected voltage, suggesting the sense line may be open or disconnected, or a glow plug has failed open-circuit preventing current flow through the sense path. This diesel engine code means the glow plug control module cannot verify proper glow ...
The most common cause of P037F (Glow Plug Sense Circuit High) is: Open-circuit glow plug with a burned-out heating element
Typical repair costs for P037F range from $60 to $500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Affects cold starting and cold-running quality but does not pose a driving hazard once the engine is running and at operating temperature. In sub-freezing conditions, the vehicle may not start if enough glow plugs are non-functional. Repair before cold weather exposure.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P037F to identify the root cause.
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Quick Info
Category
Powertrain
System
Diesel Glow Plug / Cold Start System
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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