P0675 — Cylinder 5 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 P0675 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 P0675 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for P0675 (parts and labor, USD, independent shop rates): Replace a full set of glow plugs: $250–$600; Replace one glow plug: $80–$200; Replace the glow plug relay/module: $150–$450. Overall, fixing P0675 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

What does OBD2 code P0675 mean?

Cylinder 5 Glow Plug Circuit (P0675): 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.

What is the most common cause of P0675?

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

What are the symptoms of P0675?

Drivers most often notice: rough idle until warmed up, hard starting in cold weather, white smoke after a cold start, Check Engine Light on.

Is it safe to drive with P0675?

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.

Will P0675 clear itself?

Sometimes P0675 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

When your OBD2 scanner pulls a P0675, the engine control unit has detected that the glow plug circuit for cylinder 5 is behaving outside its expected parameters. The official definition reads "Cylinder 5 Glow Plug Circuit" — a powertrain-level fault that points directly at the diesel pre-heat system. On most inline diesel engines, cylinder numbering runs from the front of the block (the pulley end) toward the transmission. V-configured diesel engines follow manufacturer-specific firing orders, so it's worth verifying the cylinder map for your specific application before diving in. Cylinder 5 might be easy to reach or buried behind the intake manifold depending on the engine bay layout — this affects labor time and your final bill.

Diesel glow plugs warm the combustion chamber during cold starts, making ignition possible when temperatures drop. The engine control module activates the glow plugs for a few seconds before cranking, then monitors the circuit to confirm each plug is drawing the correct current. When P0675 sets, it means the control unit compared live data from cylinder 5's glow plug circuit against factory calibration limits — typically over multiple drive cycles before illuminating the check engine light. Most scanners also capture a freeze frame snapshot alongside the code, recording engine RPM, load percentage, coolant temperature, and vehicle speed at the exact moment the fault occurred. That snapshot is gold for narrowing down whether the problem is environmental (cold start stress) or electrical (a genuine circuit failure).

Common Symptoms of P0675

Engine stumbles or runs rough at idle until fully warmed up
Difficulty starting, especially on cold mornings or in freezing temperatures
White exhaust smoke billowing from the tailpipe after a cold start
Check engine light remains illuminated
Glow plug warning light stays on in the instrument cluster

What Causes P0675

Damaged or deteriorated wiring harness feeding the cylinder 5 glow plug
Corroded, loose, or melted electrical connector at the glow plug
Failed glow plug relay or glow plug control module
Blown fuse protecting the glow plug bus
Burned-out glow plug element (open circuit)
Chafed wiring from heat exposure or engine vibration
Control module software requiring an update

How to Diagnose P0675

Connect an OBD2 scanner and confirm P0675 is an active or pending code. Record the freeze frame data before clearing anything — this shows the exact conditions (temperature, load, RPM) when the module first logged the fault.
Scan for any related diagnostic trouble codes. Multiple glow plug codes appearing together often point to a shared power supply or ground issue rather than individual plug failures. Check manufacturer TSB databases for known software updates or factory fixes tied to P0675 on your specific model year.
Perform a thorough visual inspection of the glow plug wiring harness and connectors. Look for cracked insulation, heat damage, corrosion buildup, or connectors that are pushed back slightly from vibration. Wiggle the harness while monitoring the scanner for live code changes.
Measure resistance across each glow plug with a digital multimeter. A functioning plug typically reads between 0.5 and 2 ohms depending on design; an infinite reading or open circuit confirms a failed plug. Test cylinder 5 specifically since P0675 targets that position.
Verify voltage presence at the glow plug rail during the pre-glow sequence using a multimeter or test light. No voltage indicates a problem upstream — fuse, relay, or control module.
After addressing any found issues, clear the code and complete a drive cycle that replicates the freeze frame conditions. If P0675 returns, the root cause is still active.

Repair Options

Glow plug replacement follows a logical hierarchy — start cheap and work up:

Replace a full set of glow plugs (recommended for high-mileage diesels): $250–$600
Replace a single failed glow plug for cylinder 5: $80–$200
Replace the glow plug relay or control module: $150–$450

How Much Does It Cost to Fix P0675

Actual repair cost hinges entirely on which component triggered P0675. At independent shop rates in the United States:

Single glow plug replacement (cylinder 5): $80–$200
Complete glow plug set replacement: $250–$600
Glow plug relay or control module replacement: $150–$450

Across all scenarios, P0675 repairs typically run between $80 and $600. The key is accurate diagnosis before purchasing parts — swapping the most expensive component first is a losing strategy when a $20 fuse or a corroded connector is the real culprit.

Can You Drive with P0675?

Once the engine reaches operating temperature, a vehicle with P0675 is generally safe to operate. The real concern is cold starting: if multiple glow plugs have failed, cranking the engine in freezing weather becomes difficult or impossible. Address this fault before cold season arrives. Prolonged operation with a dead cylinder 5 glow plug adds unburned fuel to that cylinder, potentially diluting the oil and causing cylinder wall glazing over time.