P0354: Ignition Coil D Primary/Secondary Circuit Malfunction
Quick Answer
Not safe to drive
P0354 means the ECU saw an electrical fault in the primary or secondary circuit driving ignition coil #4. Cylinder 4 isn't getting reliable spark, so expect a misfire and a flashing CEL under load.
- Severity
- Moderate · Ignition
- Estimated repair cost
- From €48 to €1450+, varies by vehicle
€48 or €1450, depending on your car.
- Replace spark plug #4 (or full set)€48–€230
- ECU repair or replacement (rare)€500–€1450
A scan shows whether P0354 is really stored on your car, which codes sit next to it and how urgent each one is. You can do this parked, with the ignition on.
A scan needs a Bluetooth OBD2 adapter (Bluetooth LE on iPhone), about €25-60; the built-in demo runs without one. See which adapter to buy
What does P0354 mean?
P0354 is a ignition-related diagnostic trouble code classified as moderate severity.
What are the symptoms of P0354?
- Rough idle, worst when cold
- Stumble or dead spot under acceleration
- Flashing check engine light when the misfire is active
- Raw fuel smell from the tailpipe
- 10 to 20 percent drop in fuel economy
- Loss of power above 3000 rpm
- Occasional pop or backfire through the exhaust
What causes P0354?
Failed ignition coil on cylinder 4
: high
Worn or fouled spark plug on cylinder 4
: high
Damaged coil connector or corroded pins
: medium
Broken wire in the coil harness (power, ground, or trigger)
: medium
Oil in the spark plug well from a leaking valve cover gasket
: low
ECU coil driver transistor failure
: low
Is it safe to drive with P0354?
No - address this immediately. You can limp home, but unburned fuel dumps into the exhaust and cooks the catalytic converter. Fix within a day or two, not weeks.
How do you diagnose P0354?
- Read all stored codes. Note any P030X misfire codes or other coil circuit codes for context.
- Swap coil #4 with coil #1 or #2, clear codes, and drive. If the fault follows the coil, replace it.
- Pull spark plug #4 and inspect gap, electrode wear, oil, fuel, or carbon fouling.
- Unplug the coil connector and check for bent pins, green corrosion, or oil contamination.
- Key on, engine off: confirm battery voltage on the coil power pin against a known good ground.
- Back-probe the ECU trigger wire while cranking and confirm a switching signal with a scope or noid/LED test light.
- Measure primary resistance (typically 0.4 to 2 ohms) and secondary (5k to 15k ohms) against factory spec.
- If coil, plug, connector, and wiring all pass, suspect the ECU driver circuit for cylinder 4.
How much does P0354 cost to fix?
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Replace ignition coil #4 | €25–€120 | €30–€90 | €55–€210 | Easy |
| Replace spark plug #4 (or full set) | €8–€80 | €40–€150 | €48–€230 | Easy |
| Repair coil harness connector or wiring | €10–€40 | €60–€180 | €70–€220 | Moderate |
| Valve cover gasket replacement (oil-fouled plug well) | €30–€120 | €120–€350 | €150–€470 | Moderate |
| ECU repair or replacement (rare) | €400–€1200 | €100–€250 | €500–€1450 | Professional |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
Full repair guides
P0354 on specific vehicles
P0354 on Ford
Ford F-150
Volkswagen
VW Golf
2006-2016
1.4 TSI (CAVD/CTHD) and 2.0 TFSI (BPY, CCTA) engines have used several coil versions, so fit the current version for your engine code, as a set rather than just cylinder 4.
P0354 on BMW
BMW 3-Series
P0354 on Toyota
Toyota Camry
P0354 on Honda
Honda Civic
Related diagnostic codes
Common questions about P0354
- Which cylinder is coil D on P0354?
- Coil D is cylinder 4 on virtually every application. On inline engines count from the front (timing) end. On V engines check the firing order and bank layout in the service data, since cylinder numbering isn't the same across manufacturers.
- Can I just swap coils to test?
- Yes, and it's the fastest test on the car. Move coil 4 to another cylinder, clear the code, and drive. If the code jumps to the new cylinder, the coil is bad. If P0354 stays, look at the plug, connector, or wiring.
- Will P0354 damage my catalytic converter?
- Yes if you keep driving on it. Raw fuel entering a hot cat overheats the substrate and melts it. A €60 coil now beats a €900 catalyst later, which is why the ECU flashes the CEL during an active misfire.
- Why did P0354 come back after I replaced the coil?
- Usually one of three things: the replacement coil is defective out of the box, the spark plug is fouled or gapped wrong, or there's a broken wire or bad pin in the connector that's still cutting the trigger signal.
- Can a bad fuel injector set P0354?
- No. A dead injector on cylinder 4 typically sets P0204 or a cylinder-4 misfire (P0304). P0354 is strictly an ignition primary or secondary circuit electrical fault, not a combustion or fuel fault.