P0671 OBD Error Code: Problem & Solutions

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Are you experiencing hard start or no start at all? Does the engine take time to heat up properly and provide optimal power? Is there a reduced level of acceleration and affected fuel economy? OBD code P0671 error refers to the problematic Glow Plug Circuit for Cylinder 1 of the engine.

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.

Error Code P0671 happens when there’s a problem in the glow plug circuit, causing the cylinder 1 glow plug to fail from heating up. This will require a complete and thorough inspection to locate the fault.

What causes this problem with the Cylinder 1 Glow Plug Circuit?

• Cylinder 1 glow plug faulty
• Damaged circuit wiring and connector
• Open or shorted glow plug circuit
• Faulty glow plug control module
• Faulty glow plug relay
• Problematic PCM

1. Glow Plug - Check for faults in the Cylinder 1 Glow Plug and replace if needed. Buy new glow plug now!
2. Glow Plug Connector - If the wiring and connectors in relation to the glow plug circuit are faulty, replace it immediately. Buy new glow plug connector now!
3. Glow Plug Relay - Inspect for glow plug relay in association to the cylinder 1 and replace it now! Buy new glow plug relay from us!
4. Starter Relay - In rare occasions the starter relay can also be faulty and should be replaced at first instance. Buy new starter relay now!
5. Engine Control Module - Faulty ECM can flash and store wrong OBD error. It’s better to get the faulty electricals replaced as soon as possible.
6. Powertrain Control Module - Damaged PCM hampers the engine timing. Find all the Powertrain related parts with us.
7. Diagnostic Tool - Find high grade diagnostic tools to detect the OBD error code from us. Visit us today to grab amazing deals.
8. Engine Wiring Connector - Check for faulty wiring and connector and replace it as required. Buy new connector now!

It is essential to know the symptoms of an issue as only then you would be able to solve the problem. So that’s why we have listed out some major symptoms of OBD Code P0671 here:

Common Symptoms

• Hard starting or no start condition when sitting long enough
• Engine lacks power until it heats up completely
• Engine hesitates when accelerating
• Engine miss due to cylinder head temperature being colder than normal
• No preheat period, preheat light doesn’t go off

Here are some ways with the help of which you will be able to correct the OBD Code P0671

• Glow Plug Replacement
• Glow Plug Relay/ Starter Relay Replacement
• Faulty Wiring and Connector Replacement
• Faulty Starter Replacement

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Here are some steps which you should follow in order to diagnose this fault code:

• Make use of a digital volt ohm meter (DVOM) for the complete test. Continue through the tests until the problem is confirmed. You will also need a basic OBD code scanner to reset the computer and erase the code.
• Check the glow plug by disconnecting the wire connector on the plug. Place the DVOM on ohms and place the red lead on the glow plug terminal and the black lead on a good ground. The range is .5 to 2.0 ohms (verify the measurement for your application by referring to a factory service manual). If it is out of range replace the glow plug.
• Check the resistance in glow plug wire to the glow plug relay buss bar on the valve cover. Notice the relay (looks like a starter relay) has a large gauge wire leading to a buss bar where all the glow plug wires are attached.
• Test the wire to the number one glow plug by placing the red lead on the buss bar number one wire and the black lead to the glow plug side. Again, .5 to 2.0 ohms with 2 ohms being the highest resistance. If it’s higher replaced the wire lead to the glow plug from the buss bar. Notice also that these leads from the buss bar to plugs are fusible links. Reconnect the wires.
• Check the same wires for looseness, cracks or missing insulation. Connect the code scanner to the OBD port under the dash and turn the key to the "on" position with the engine off. Clear the codes.
• Also check for faulty PCM and repair or reprogram it as required as it might be the reason for wrong codes getting stored in system.

Common Mistakes When Diagnosing the P0671 Code

• Glow plug control module failure
• Glow plug failure
• Glow plug wiring harness failure