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P0671 is a diagnostic trouble code (DTC) for "Cylinder 1 Glow Plug Circuit". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.
The P0671 code indicates that the PCM has detected an abnormal voltage reading from the glow plug circuit in cylinder 1.
Diesel engines require glow plugs to heat cylinders before and during the ignition process. Each cylinder has a glow plug, which uses battery voltage to heat up. The PCM controls the activation of the glow plug circuit, and monitors the activity with voltage readings. If the voltage reading does not match the manufacturer’s specifications, it is likely that the glow plug is not working properly to heat the engine. In this case, the PCM will store the P0671 code.
There are many things that can cause the P0671 code. These include:
Most of the time, the vehicle’s owner will notice that the vehicle is taking longer to start, and that the glow plug indicator light never deactivates, or stays on for longer than normal. White smoke may be observed upon start-up; the engine may be considerably louder than normal during start-up; the engine may misfire; and the Check Engine lamp will be illuminated.
After an OBD-II scanner detects the P0671 code, a technician should begin with a visual inspection of the electrical components, repairing or replacing any damaged components as necessary. After this, and any other repair process, the PCM should be cleared, and the system should be retested, to find out if the repair solved the issue.
If the electrical components were not to blame, the mechanic will begin checking the glow plug connector, the glow plug itself, and fuses, for proper function. Activating the glow plug heater after checking each of these repairs will show the mechanic if there is a short in the circuitry, or if the parts themselves were to blame.
While glow plugs themselves, and the electrical components within the glow plug circuit, are often to blame for the P0671 code, many technicians report that glow plug timers and relays are frequently replaced without checking the electrical components and glow plugs.
The P0671 code represents a serious issue that affects the drivability of the vehicle. If left unrepaired, the vehicle may not start properly, or at all, in the future.
There are many ways that a technician can address a P0671 code detection. They include:
When repairing any issue related to the glow plugs, safety is very important. When activated, glow plugs become extremely hot. Technicians should exercise caution when testing glow plugs for proper functionality.
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