What causes fault code P0350?

• Most likely: Faulty ignition coil (or ignition pack) with internal short or open circuit • Likely: Damaged wiring or loose connectors in the ignition harness • Possible: Corroded ignition relay or poor engine block/chassis ground • Rare: Defective Engine Control Unit (ECU) ignition driver failure

Powertrain (Engine & Gearbox)Standard EOBD

P0350 - Ignition Coil Primary/Secondary Circuit Malfunction

Q: What are the symptoms of fault code P0350?

• Check engine light (MIL) illuminated • Engine misfiring (rough idle or jerking) • Significant loss of power (Limp home mode) • Hard starting or engine stalling • Smell of unburned fuel from exhaust • Increased fuel consumption

Q: How do you fix fault code P0350?

STEP 1: Perform a visual inspection of the ignition coil connectors and wiring. Look for cracks in the coil housing or burn marks. STEP 2: Verify supply voltage at the coil with ignition ON (should be battery voltage ~12.6V). Check ground points (resistance should be <0.5 Ohms). STEP 3: Measure the primary winding resistance with a multimeter (typically 0.5–2.0 Ohms, refer to service manual). STEP 4: Use an oscilloscope to measure the trigger signal from the ECU. The pulse should be sharp and consistent. STEP 5: If the coil is confirmed faulty, replace the unit. If the signal is absent from the ECU, internal driver repair or ECU replacement may be necessary.

Last updated:1 February 2026

Related:Ignition Coil, Spark Plug, Engine Control Unit (ECU), Wiring Harness, Relay

System

Powertrain (Engine & Gearbox)

Related Fault Codes

P0300

Random or Multiple Cylinder Misfire Detected

P0301

Cylinder 1 Misfire Detected

P0302

Cylinder 2 Misfire Detected

P0303

Cylinder 3 Misfire Detected

Technical Description

P0350 is a generic OBD-II code indicating that the Engine Control Unit (ECU) has detected a malfunction in the primary or secondary circuit of the ignition coil(s). The primary circuit involves the low-voltage wiring from the ECU/ignition module to the coil, while the secondary circuit refers to the high-voltage output to the spark plugs. The ECU monitors the flyback voltage during coil discharge; if the signal is absent or outside the expected duty-cycle/amplitude parameters, the code is triggered. Unlike cylinder-specific codes (P0351-P0362), P0350 suggests a more systemic electrical fault in the ignition supply or grounding.

Possible Causes

Faulty ignition coil (or ignition pack) with internal short or open circuit

Damaged wiring or loose connectors in the ignition harness

Corroded ignition relay or poor engine block/chassis ground

Defective Engine Control Unit (ECU) ignition driver failure

Symptoms

Check engine light (MIL) illuminated

Engine misfiring (rough idle or jerking)

Significant loss of power (Limp home mode)

Hard starting or engine stalling

Smell of unburned fuel from exhaust

Increased fuel consumption

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P0350 - Ignition Coil Primary/Secondary Circuit Malfunction

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P0350 - Ignition Coil Primary/Secondary Circuit Malfunction

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