What is OBD-II Code P0681 – Cylinder 11 Glow Plug Circuit/Open
As a mechanic, one of the most valuable diagnostic tools in my arsenal is the OBD-II system, which allows me to identify and troubleshoot issues with the electronic systems in a vehicle. One of the most common OBD-II codes that I see is P0681, which relates to the glow plug circuit in a diesel engine. In this article, I will explain what this code means, how to diagnose the problem, and how to repair it.
What is a Glow Plug?
Before we dive into the specifics of code P0681, it’s important to understand what a glow plug is and what it does. Glow plugs are small heating elements that are used to warm up the air inside a diesel engine’s combustion chamber before starting the engine. Because diesel fuel is less volatile than gasoline, it requires a higher temperature to ignite. By using glow plugs to preheat the air, diesel engines are able to start more quickly and run more smoothly.
What is OBD-II Code P0681?
Code P0681 is a generic OBD-II code that indicates an issue with the glow plug circuit in a diesel engine. Specifically, it means that the ECM (engine control module) has detected an open circuit in the wiring for cylinder 11’s glow plug. This can happen if the glow plug itself has failed, if there is a problem with the wiring, or if there is an issue with the ECM or a related component.
How to Diagnose Code P0681
Diagnosing a problem with the glow plug circuit can be a bit tricky, as there are several different components that could be causing the issue. Here are the steps that I typically follow when diagnosing a P0681 code:
Step 1: Check the Glow Plug
The first thing that I do is check the glow plug itself to see if it has failed. This can be done by removing the glow plug and testing it with a multimeter. A healthy glow plug should have a resistance of less than 5 ohms. If the resistance is too high or infinite, the glow plug will need to be replaced.
Step 2: Check the Wiring
If the glow plug is functioning properly, the next step is to check the wiring to make sure that there isn’t a problem. This can be done by using a multimeter to test for continuity between the glow plug and the ECM. If there is no continuity, there may be a break in the wiring that will need to be repaired.
Step 3: Check the ECM
If the glow plug and the wiring are both functioning properly, the problem might be with the ECM itself. To test this, I usually use a diagnostic tool to communicate with the ECM and check for any error codes or other issues. If the ECM is the problem, it may need to be replaced.
How to Repair Code P0681
Once you have identified the source of the problem, repairing a P0681 code is usually a relatively straightforward process. Here are the steps that I typically follow:
Step 1: Replace the Glow Plug
If the glow plug has failed, it will need to be replaced. This typically involves removing the old glow plug and installing a new one using a special socket designed for glow plugs.
Step 2: Repair the Wiring
If there is a break in the wiring, it will need to be repaired. This can usually be done by splicing a new section of wire onto the existing wire and sealing the connection with heat shrink tubing or electrical tape.
Step 3: Replace the ECM
If the ECM is the problem, it will need to be replaced. This is usually a more involved process that requires programming the new ECM to work with the vehicle’s existing systems.
FAQs
Q: What happens if I ignore a P0681 code?
A: Ignoring a P0681 code can lead to a variety of issues, including reduced fuel efficiency, difficulty starting the engine, and decreased engine performance. It’s important to have this issue diagnosed and repaired as soon as possible to avoid further damage to your vehicle.
Q: How often do glow plugs need to be replaced?
A: The lifespan of a glow plug can vary depending on a number of factors, including the type of vehicle, driving conditions, and maintenance habits. In general, glow plugs should be inspected and replaced every 50,000 to 100,000 miles.
Q: Can I replace a glow plug myself?
A: While it is possible to replace a glow plug yourself, it can be a tricky process that requires some specialized tools and knowledge. If you’re not comfortable working on your own vehicle, it’s best to take it to a professional mechanic.
Q: How much does it cost to repair a P0681 code?
A: The cost of repairing a P0681 code can vary depending on the source of the problem and the type of vehicle involved. In general, you can expect to pay anywhere from $100 to $500 for parts and labor.
Q: What other issues can cause a P0681 code?
A: While a failed glow plug or wiring issue is the most common cause of a P0681 code, other issues such as a failed relay, corroded battery terminals, or a faulty alternator can also cause this code to appear. It’s important to have a professional mechanic diagnose the problem to ensure that the correct issue is being addressed.
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