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P0351 on Cadillac: Symptoms, Causes & Fix

Ignition Coil A Primary/Secondary Circuit Malfunction

Official technical diagnostic wire for fault code P0351 specifically affecting Cadillac vehicles (Escalade, Escalade-V, CT5, CT5-V Blackwing, CT4).

Sensor Voltage Ref
0.1V – 5.0V Ref
Cadillac Factory Standard
CAN Bus Speed
500 kbps CAN-FD
ISO 15765-4 Diagnostic Bus
Drivability Status
Not Recommended
Critical urgency level
Est. Repair Cost
$100 - $350 (DIY: $30 - $90)
Parts & Labor DIY
Model-Specific Diagnostic Wires

Select Your Cadillac Model for P0351:

6 Models Available

1. Common Symptoms on Cadillac Vehicles

When Cadillac Engine Control Modules (ECM) trigger fault code P0351, drivers typically report:

Flashing Check Engine Light on Cadillac Powertrains
Severe engine shuddering and jerking under acceleration on Cadillac Powertrains
Hard misfire on Cylinder 1 (accompanied by P0301) on Cadillac Powertrains
Strong smell of unburned gasoline from exhaust on Cadillac Powertrains

2. Root Causes on Cadillac Engines

Historical diagnostic claims across Cadillac engines point to the following failure distribution:

55%
Failed ignition coil pack on Cylinder 1 (Coil A) (Cadillac OEM Part)
25%
Broken or melted wiring harness to ignition coil 1 (Cadillac OEM Part)
12%
Corroded or broken terminal pins in coil electrical connector (Cadillac OEM Part)
8%
Burned ignition driver transistor (IGBT) inside the ECM/PCM (Cadillac OEM Part)

3. Step-by-Step Fix Protocol for Cadillac

01
Locate Coil A (Cylinder 1 Ignition Coil)

Identify Cylinder 1 ignition coil pack mounted on the valve cover. on Cadillac engines.

Required Tool: Flashlight
02
Perform Coil Swap Test

Swap Coil 1 with Coil 2. Clear codes and restart engine. If code switches to P0352 (Coil B), the ignition coil is 100% defective. on Cadillac engines.

Required Tool: 10mm Socket, Ratchet, OBD-II Scanner
03
Test Wiring Harness if Code Remains P0351

Check for 12V battery power, chassis ground, and 5V trigger pulse from the PCM on the 3-pin / 4-pin harness plug. on Cadillac engines.

Required Tool: Digital Multimeter, Test Light
04
Replace Ignition Coil & Spark Plug

Install a new OEM ignition coil (e.g. Denso, Motorcraft, Delphi) and replace the spark plug on Cylinder 1. on Cadillac engines.

Required Tool: 5/8 Spark Plug Socket, 10mm Socket, Ratchet
05
Clear Trouble Codes and Road Test

Clear DTCs and verify smooth acceleration under load. on Cadillac engines.

Required Tool: OBD-II Scanner
Recommended Parts & Testing Tools

Equipment for Diagnosing Cadillac (P0351)

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OEM Ignition Component

Direct-Fit Laser Iridium Spark Plugs (Set of 4/6)

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Pre-gapped iridium spark plugs engineered to restore smooth combustion on Cadillac.

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Ignition Service Tool

Magnetic Swivel Spark Plug Socket Set

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360-degree magnetic swivel socket prevents ceramic plug cracks inside deep engine spark wells.

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4. Cadillac P0351 Frequently Asked Questions

What does code P0351 mean on a Cadillac?

On Cadillac vehicles, P0351 indicates that the Engine Control Module (ECM) detected ignition coil a primary/secondary circuit malfunction. This typically points to Failed ignition coil pack on Cylinder 1 (Coil A) or Broken or melted wiring harness to ignition coil 1.

Can I continue driving my Cadillac with code P0351?

No. Cylinder 1 ignition coil has failed completely, causing an active misfire and dumping unburned fuel into the catalytic converter. Because this code carries a Critical severity rating on Cadillac powertrains, we recommend scanning live data values promptly to prevent secondary damage.

How much does it cost to fix code P0351 on a Cadillac?

Estimated DIY parts cost ranges from $100 - $350 (DIY: $30 - $90), while professional shop repairs at an authorized Cadillac dealership or independent specialist typically range from $180 to $380 including diagnostic labor.