P037D Glow Plug Sense Circuit
OBD-II Trouble Code Technical Description
Glow Plug Sense Circuit
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles that have glow plugs (diesel engine vehicles). Brands of vehicles may include but are not limited to Ford, Dodge, Mazda, VW, Ram, GMC, Chevy, etc. Although generic, the specific repair steps may vary depending on make/model/engine. Anecdotally this code seems more common on Ford vehicles.
The glow plugs and their associated harnesses and circuits are part of a system that is responsible for generating heat in the combustion chamber prior to cold startups.
Essentially , the glow plug is similar to an element on a stove-top. These are incorporated in diesel engines because diesel engines do not use a spark plug to ignite the fuel/air mixture. Rather, they use compression to generate enough heat to ignite the mixture. For this reason, diesel engines need the glow plugs’ help on cold starts.
The ECM throws P037D and associated codes when it monitors a condition outside of a specific range within the glow plug circuit. Most of the time, I would say this would be an electrical issue but some mechanical problems could affect your glow plug circuit on some makes and models. P037D Glow Plug Sense Circuit code is set when the ECM monitors one or more values outside a specific range.
An example of a glow plug:
NOTE: If other dash lights are currently illuminated (I.E: Traction control, ABS, etc..), this may be a sign of another potentially bigger problem. In this case, you should bring your vehicle to your reputable shop where they can plug in with a proper scan tool to avoid doing any unnecessary harm.
This trouble code is closely related to P037E and P037F.
What is the severity of this DTC?
Generally speaking, the severity of this code would be moderate but depending on the scenario, it may be severe. For example, if you reside in moderate to extreme cold conditions, repetitive cold starts with malfunctioning glow plugs will eventually cause unnecessary damage to your internal engine components.
What are some of the symptoms of the code?
Symptoms of a P037D engine code may include:
Hard starts in the morning or when cold Abnormal engine noises on start-up Poor performance Engine misfiring Poor fuel mileageWhat are some of the common causes of the code?
Causes for this code may include:
Broken or damaged wiring harness Fusible link burnt/defective Glow plug defective ECM issue Pin/connector problem. (i.e. corrosion, overheating etc.)What are some troubleshooting steps?
Be sure to check for technical service bulletins (TSBs) for your vehicle. Getting access to a known fix can save you time and money during diagnosis.
Tools
Whenever you are working with electrical systems, some of the basic tools that are a good idea to have are:
OBD code reader Multimeter Basic socket set Basic ratchet and wrench sets Basic screwdriver set Rag/shop towels Battery terminal cleaner Service manualSafety Tips
Let engine cool Chalk wheels Wear PPE (Personal protective equipment)Basic Step #1
First thing i would do in this situation, would be pop the hood and smell for any kind of irregular burning scents. If present, this may be the trail to your problem. Most times, if there is excessive burning smells it means something is overheating. Carefully follow the smell, if you see any burnt wire coatings or melting plastic around fuse boxes, fusible links, etc. this will need to be addressed first.
NOTE: Visually inspect all ground straps and look for corroded or loose ground connections.
Basic Step #2
Locate and follow the glow plug circuit harness. These harnesses are exposed to extr
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