Glow Plug Heater Circuit (Cylinder 3)
Glow plug for cylinder 3 has a circuit issue.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The glow plug for cylinder 3 isn't getting the right power or isn't working at all when you start the engine, especially in cold weather.
What the computer is actually seeing
The engine control module (ECM) monitors the voltage to the glow plug and expects around 12 volts while the glow plugs are activated. If it sees less than 8 volts or none, it triggers this code.
What a healthy reading looks like
12V at the glow plug terminal when activated; less than 0.5 ohm resistance in the glow plug wire; glow plug should draw around 10-15 amps.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check the wiring and connectors to glow plug 3 for signs of damage or corrosion. Repair or replace as needed. Decision: Is there damage? If yes, fix and retest code. If no, proceed to step 2.
- 22. Use a multimeter to measure the voltage at the glow plug terminal while cranking the engine. Expected: around 12V when active. Decision: Is voltage present? If yes, proceed to step 3. If no, check the wiring back to the ECM and the ECM output.
- 33. Disconnect glow plug 3 and measure resistance across the glow plug. Expected: 0.5 ohms or less. Decision: Is resistance OK? If yes, the glow plug is fine. If no, replace the glow plug.
Common causes
- Faulty glow plug for cylinder 3
- Open circuit in glow plug wiring
- Corroded or loose connections at the glow plug or ECM
- Faulty ECM
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's moderate, so you can drive but expect harder starts, especially in cold conditions.
Will this code come back after clearing?
If the underlying issue isn't fixed, it will likely return.
Why does it pair with other glow plug codes?
Codes like P0670-P0675 indicate issues with various cylinders, often due to similar wiring problems or ECM faults.
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