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.
DTC/P0670·Audi
P0670 on Audi: Causes, Symptoms and Fix Cost
Quick Answer
Low SeveritySafe to drive (short-term)Audi
P0670 on a Audi 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.
Repair cost on Audi€2 - €425
What does P0670 mean on a Audi?
Audi A4 TDI
2004-2019The A4 TDI shares the VAG monitoring control module with the Golf and Passat. P0670 typically points to the module or its connector at higher mileage. The module is often mounted low near the engine where moisture and road salt can corrode the connector, so inspect the plug and pins before condemning the unit.
What causes P0670 on a Audi?
Beyond the generic causes listed on the main P0670 page, these are the Audi-specific patterns we see most often:
Audi A4 TDIVAG glow plug control module failure
Audi A4 TDIConnector corrosion from moisture and road salt
How to diagnose P0670 on a Audi with OBD2
Follow these steps to pinpoint the root cause of 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 on a Audi? (EUR)
Estimated repair costs on a Audi (Audi parts and labour typically run 15% above the average for this code).
Prices estimated as of May 2026. Costs vary by region, vehicle, and shop.
Related codes that often appear with P0670 on Audi
These codes commonly cluster with P0670 on Audi vehicles:
FAQ: P0670 on Audi
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 the car will likely fail inspection until the fault is fixed.
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.
Looking for the full P0670 reference (all makes, full diagnosis flow, complete repair cost matrix)?
See the main P0670 guideSkanyx · Audi
Diagnosing P0670 on your Audi?
Connect any Bluetooth OBD2 adapter, scan for codes, and get AI-powered diagnostics with severity ratings and repair cost estimates.
Download Skanyx