P0676 — Cylinder 6 Glow Plug Circuit

powertrain (engine/transmission)

Is it safe to drive?

Short-term driving is OK Safe to drive once the engine is started and warmed up. The main risk is cold-weather starting: with several dead plugs the engine may not start on a cold morning. Fix before winter.

How to diagnose with an OBD scanner

Read the code and freeze frame Connect an OBD2 scanner, confirm P0676 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many P0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the diesel glow plug system for damage, corrosion, chafing or poor contact.
Subsystem check Measure resistance of each glow plug — an open plug reads infinite resistance.
Subsystem check Check voltage at the glow plug rail during the pre-glow phase.
Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm P0676 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0676 (parts and labor, USD, independent shop rates): Replace the glow plug relay/module: $150–$450; Replace one glow plug: $80–$200; Replace a full set of glow plugs: $250–$600. Overall, fixing P0676 usually costs between $80 and $600. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

How much does it cost to fix P0676?

Replace the glow plug relay/module — $150–$450; Replace one glow plug — $80–$200; Replace a full set of glow plugs — $250–$600. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

How do I diagnose P0676 myself?

Start with a scan: confirm P0676, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the diesel glow plug system, and verify the suspect component against live data before buying parts.

What is the most common cause of P0676?

The most common causes are: corroded glow plug connectors, damaged glow plug wiring or connector, faulty glow plug relay or control module.

Is it safe to drive with P0676?

Safe to drive once the engine is started and warmed up. The main risk is cold-weather starting: with several dead plugs the engine may not start on a cold morning. Fix before winter.

What does OBD2 code P0676 mean?

Cylinder 6 Glow Plug Circuit (P0676): a powertrain (engine/transmission) fault affecting the diesel glow plug system. The car is usually drivable while you plan the repair. Most often caused by corroded glow plug connectors, damaged glow plug wiring or connector, faulty glow plug relay or control module.

Diesel engines rely on glow plugs to fire up in cold weather. Unlike spark plugs in gasoline engines, these pencil-thin heating elements warm the combustion chamber so diesel fuel can ignite properly. When the powertrain control module detects a problem with cylinder 6's glow plug circuit, it logs trouble code P0676.

The control module watches the glow plug circuit constantly during startup and initial warm-up. Each time you crank the engine, it sends current to the plugs and monitors resistance. If cylinder 6 shows an open circuit, short circuit, or out-of-spec resistance across enough drive cycles, P0676 gets stored and the check engine light illuminates. The module also saves freeze frame data—snapshot values showing RPM, engine load, coolant temperature, and vehicle speed at the exact moment the fault appeared. That snapshot is your best starting point when you hook up a scanner.

Glow plug numbering follows engine orientation. On inline diesels, cylinder 1 sits at the front (belt end) with cylinders numbered sequentially back toward the transmission. V-configured engines vary by manufacturer, so you'll need your specific firing order diagram. Cylinder placement matters practically: some engines require pulling the intake manifold to reach cylinder 6, which adds labor time and cost to any repair.

Symptoms of P0676

Thick white smoke billowing from the tailpipe on cold starts
Glow plug warning lamp remains illuminated after the engine warms
Rough, uneven idle that smooths out once operating temperature is reached
Check Engine Light stays on
Difficulty starting, especially when temperatures drop below freezing

What Causes P0676?

Corrosion or moisture intrusion at the cylinder 6 glow plug electrical connector
Burned-out or mechanically failed glow plug
Defective glow plug control relay or module
Blown fuse protecting the glow plug circuit
Damaged wiring harness or connector housing in the glow plug circuit

How to Diagnose P0676

Connect an OBD2 scanner, verify P0676 is present in the fault memory, and record all freeze frame data before clearing anything.
Scan for additional diagnostic trouble codes. Related codes often point to the actual root cause rather than the symptom.
Check for any applicable technical service bulletins for your specific make, model, and model year—manufacturers publish TSBs for known issues that may include software updates or revised repair procedures.
Perform a thorough visual inspection of the wiring harness and connectors feeding the glow plug system, looking for chafed insulation, broken wires, corrosion buildup, or loose connections.
Measure resistance across each glow plug with a multimeter. An open-circuit reading indicates a failed plug.
Clear P0676, complete a drive cycle that reproduces the conditions captured in the freeze frame data, and verify the code does not return.

Repair Options for P0676

Address the most probable causes before committing to expensive replacements:

Replace glow plug relay or control module: $150–$450
Replace single glow plug: $80–$200
Replace complete glow plug set: $250–$600

Total Repair Cost for P0676

Your final invoice depends entirely on which component triggered the fault. Parts and labor at independent shop rates typically break down as follows:

Glow plug relay or module replacement: $150–$450
Single glow plug replacement: $80–$200
Full glow plug set replacement: $250–$600

Most P0676 repairs fall between $80 and $600. The key is performing a proper diagnosis before purchasing parts—the priciest scenario is rarely where you should start.

Can You Drive with P0676?

Once the engine reaches operating temperature, driving presents no immediate safety concern. The real risk is cold-weather starting: a dead cylinder 6 glow plug makes cranking harder in freezing conditions, and multiple failed plugs may prevent startup altogether. Schedule the repair before cold weather arrives.