P0354
Ignition Coil D Primary/Secondary Circuit Malfunction
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The P0354 code indicates a malfunction in the circuit of Ignition Coil D, which controls spark for cylinder 4. The PCM monitors the voltage feedback from each ignition coil circuit and sets a specific code when it detects an open, short, or otherwise abnormal signal in a particular coil's circuit.
On 4-cylinder engines, this code refers to the last cylinder. On V6 and V8 engines, cylinder 4 may be on either bank depending on the manufacturer's numbering convention. A flashing Check Engine light means active misfires are occurring and the catalytic converter is at risk — drive gently and get it fixed promptly.
The repair process is identical to the other coil codes (P0351-P0353): perform a coil swap test to confirm the faulty component, then replace the coil and spark plug together. This is consistently rated as one of the easiest DIY automotive repairs. If multiple coil codes appear simultaneously (P0351 through P0354 all at once), the problem is less likely to be the coils themselves and more likely a shared power supply issue, a bad ignition relay, or a PCM fault — have a professional diagnose it in that case.
Severity
Symptoms
- •Engine misfires or runs rough
- •Check Engine light is on (may flash)
- •Vibration felt at idle
- •Reduced acceleration and power
- •Exhaust smells of unburned fuel
- •Worsened fuel economy
Likely Causes
The ignition coil for cylinder 4 has failed internally, with an open or shorted winding preventing proper spark generation for that cylinder.
Physical damage, corrosion, or heat damage to the wiring or connector serving the cylinder 4 ignition coil is interrupting the circuit.
A degraded spark plug on cylinder 4 creates excessive resistance, causing the coil to work harder and eventually fail.
The PCM's internal coil driver for cylinder 4 has failed, preventing it from energizing and de-energizing the coil properly.
A blown ignition fuse, faulty relay, or corroded ground is starving the cylinder 4 coil of the voltage or ground it needs to operate.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Replace the ignition coil for cylinder 4
- Replace the spark plug for cylinder 4
- Repair or replace damaged wiring and connectors
- Swap the coil with another cylinder to isolate the fault
Shop Parts
Videos
Causes and Fixes P0354 Code: Ignition Coil "D" Primary/Secondary Circuit
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P0354 CODE: What Does It Mean & How to Fix It
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