Can I drive with a P0670 code?

Yes. The glow plug control module only matters for cold starting a diesel. Once the engine is warm it runs normally. You will get harder cold starts, more startup smoke, and it is worth fixing before a periodic technical inspection.

What is the difference between P0670 and P0380?

P0380 is a general glow plug heater circuit "A" fault, while P0670 points specifically at the glow plug control module circuit. They often appear together. P0670 steers you toward the module, its wiring, and its power/ground rather than an individual plug.

Can a bad glow plug cause P0670?

Sometimes. A shorted glow plug can overload the control module and set a module circuit code. Bench-test each plug with a multimeter before replacing the module so you do not pay for a module that a failed plug killed.

How much does a glow plug control module cost?

The module itself usually costs 60-220 EUR depending on the vehicle, with another 60-150 EUR labor at a shop. Check the fuse, wiring, and ground first, since those are far cheaper fixes that produce the same code.

Does generic OBD2 show which glow plug is bad?

No. Generic OBD2 gives you the circuit code only. Per-cylinder glow plug status is manufacturer-extended Mode $22 data. To find the failed plug, bench-test each one with a multimeter; a healthy plug reads about 0.5-2 ohm.

P0670: Glow Plug Control Module Circuit

Quick Answer

Safe to drive (short-term)

P0670 is a diesel-only code meaning the engine control unit detected a fault in the glow plug control module circuit. The control module switches high current to the glow plugs that preheat the combustion chambers for cold starting and reports back to the ECU. The code points to the module itself, its supply or control wiring, or its ground rather than to one specific plug. Repairs typically run 70-350 EUR.

Severity: Low · Electrical
Estimated repair cost: From €2 to €370+, varies by vehicle

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What does P0670 mean?

P0670 is a electrical-related diagnostic trouble code classified as low severity.

What are the symptoms of P0670?

Check engine light or glow plug indicator illuminated
Hard or extended cranking on cold starts
White or grey smoke from the exhaust when starting cold
Rough idle and misfire during the first minute after cold start
Glow plug warning lamp flashing on some vehicles
Higher exhaust emissions until the engine warms up

What causes P0670?

Failed glow plug control module
: high
Open, shorted, or corroded wiring between the ECU and the control module
: medium
Poor power supply or ground to the control module
: medium
Blown fuse feeding the glow plug control module
: medium
Corroded module connector pins
: low
Faulty ECU control output to the module (rare)
: low

Is it safe to drive with P0670?

Generally yes, for short-term driving. Safe to drive once the engine is warm. The glow plug control module only matters for cold starting a diesel, so the engine runs normally after warmup. Expect harder cold starts, longer cranking, and more white startup smoke. A stored emissions-related fault is the kind of defect that gets a car rejected at inspection, so have it fixed before you book one.

How do you diagnose P0670?

Read the stored code and freeze frame with Skanyx or any ELM327 adapter to confirm P0670 and note the conditions when it set
Check the fuse feeding the glow plug control module, as a blown fuse can trigger the circuit fault
Verify battery voltage at the module power supply pin and confirm a clean ground with a multimeter
Inspect the connector and wiring between the ECU and the control module for corrosion, broken pins, or chafing
Bench-test the glow plugs themselves with a multimeter (a healthy plug reads roughly 0.5-2 ohm) to rule out a dead plug dragging down the circuit before condemning the module
Remember that detailed control module and per-plug status is manufacturer-extended (Mode $22) data that generic OBD2 does not expose, so module replacement is confirmed by supply, ground, and wiring checks plus the plug bench test

How much does P0670 cost to fix?

Repair	Parts Cost	Labor Cost	Total Estimate	DIY Difficulty
Replace control module fuse (DIY)	€2–€8	€0–€0	€2–€8	Easy
Repair wiring/connector to control module (DIY)	€5–€30	€0–€0	€5–€30	Moderate
Replace glow plug control module (shop)	€60–€220	€60–€150	€120–€370	Moderate
Diagnose and repair control module wiring/ground (shop)	€10–€60	€80–€180	€90–€240	Professional

Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.

P0670 on specific vehicles

P0670 on Volkswagen

Volkswagen Golf TDI

See Volkswagen-specific causes & cost

P0670 on BMW

BMW 320d

See BMW-specific causes & cost

P0670 on Audi

Audi A4 TDI

See Audi-specific causes & cost

P0670 on Mercedes-Benz

Mercedes-Benz (OM651 diesel)

See Mercedes-Benz-specific causes & cost

Common questions about P0670

Can I drive with a P0670 code?: Yes. The glow plug control module only matters for cold starting a diesel. Once the engine is warm it runs normally. You will get harder cold starts, more startup smoke, and it is worth fixing before a periodic technical inspection.
What is the difference between P0670 and P0380?: P0380 is a general glow plug heater circuit "A" fault, while P0670 points specifically at the glow plug control module circuit. They often appear together. P0670 steers you toward the module, its wiring, and its power/ground rather than an individual plug.
Can a bad glow plug cause P0670?: Sometimes. A shorted glow plug can overload the control module and set a module circuit code. Bench-test each plug with a multimeter before replacing the module so you do not pay for a module that a failed plug killed.
How much does a glow plug control module cost?: The module itself usually costs 60-220 EUR depending on the vehicle, with another 60-150 EUR labor at a shop. Check the fuse, wiring, and ground first, since those are far cheaper fixes that produce the same code.
Does generic OBD2 show which glow plug is bad?: No. Generic OBD2 gives you the circuit code only. Per-cylinder glow plug status is manufacturer-extended Mode $22 data. To find the failed plug, bench-test each one with a multimeter; a healthy plug reads about 0.5-2 ohm.

Read our detailed guides

Scan your car with Skanyx to diagnose P0670