The firing order for the 2012 Nissan Sentra is 1-3-4-2. This sequence applies to its inline-4 engines of that year, including the 2.0-liter MR20DE and the 2.5-liter QR25DE, and it is the order in which the ignition events occur across the cylinders.
Engine options in the 2012 Sentra
The Sentra offered two four-cylinder engines in 2012. While both share the same basic layout, the ignition system follows the same firing sequence: 1-3-4-2.
- 2.0-liter MR20DE inline-4 — Firing order: 1-3-4-2.
- 2.5-liter QR25DE inline-4 — Firing order: 1-3-4-2.
In both engines, ensure ignition coils or spark plug wires (for models using coil packs or plug wires) are connected in the correct sequence, aligning with cylinders 1 through 4 in the order 1-3-4-2.
Verifying and applying the firing order
When performing maintenance, confirm the firing order with the vehicle’s service manual or a factory wiring diagram. The exact cylinder numbering is defined by Nissan and might vary slightly by engine family, so refer to the manual to be sure.
Cylinder numbering and orientation
In most Nissan inline-4 engines, cylinder 1 is located toward the front of the engine. The order 1-3-4-2 should be preserved when installing ignition coils, spark plugs, or wires. If you’re unsure, consult the service manual or a Nissan dealer for the correct layout.
Practical steps for spark plugs and ignition coils
If you’re replacing spark plugs or ignition coils, follow these steps in the context of the firing order to avoid misfiring and engine damage.
- Disconnect the negative battery terminal to prevent short circuits while working.
- Identify and label each ignition coil or spark plug wire according to cylinder number, using the 1-3-4-2 sequence as a reference.
- Remove the coil packs and/or spark plugs for the cylinders being serviced, noting their positions.
- Install new spark plugs to the recommended torque and reinstall the ignition coils in the correct cylinders, rechecking the order to ensure 1-3-4-2 is preserved.
- Reconnect the battery, start the engine, and listen for smooth operation; if misfiring occurs, recheck wiring order and torque specs.
Maintaining the correct firing order is essential for engine performance and reliability. The Sentra’s inline-4 engines are designed to run efficiently when the sequence is kept consistent, especially during maintenance or tune-ups.
Summary
The 2012 Nissan Sentra uses a firing order of 1-3-4-2 for its inline-4 engines, including both the 2.0L MR20DE and the 2.5L QR25DE. Always verify the cylinder numbering in your service manual and follow proper torque specifications when replacing plugs or coils. Correct wiring ensures smooth running and avoids misfires.