On a 2009 Versa with the MR18DE 1.8L inline-4 engine, Cylinder 4 is the rear-most cylinder in the engine block, closest to the firewall when viewed from the front of the vehicle. In inline-4 layouts, numbering runs from the front of the engine toward the back.
Understanding the cylinder layout
Most inline-4 Nissan engines label cylinders from the front of the engine (nearest the radiator) to the back. This means Cylinder 1 is at the front, and Cylinder 4 sits toward the rear near the firewall. This orientation helps you identify spark plugs, coils, and injectors without removing the entire intake manifold.
Locating cylinder 4 on a 2009 Versa
The following steps guide you to identify cylinder 4 by physical location and components. Use these if you are changing spark plugs, coils, or inspecting wiring.
- Identify the front of the engine (the side facing the radiator). Cylinder 1 sits closest to this end.
- Count cylinders from front to back along the head: cylinder 2, then cylinder 3, and cylinder 4 at the rear toward the firewall.
- If your Versa uses coil-on-plug ignition, locate the coil(s) and spark plugs; the rear-most coil/spark plug corresponds to cylinder 4.
- Consult a diagram on the valve cover or the official service manual to confirm the exact mapping for your VIN and engine variant.
Access to cylinder 4 may require the removal of components such as the engine cover or part of the intake manifold to reach the spark plug or coil. Always ensure the engine is cool and disconnect the battery when performing electrical work.
Verification tips
If you want an extra check, look for a stamped diagram on the valve cover or use a trusted repair guide or Nissan service manual. Some models label the cylinder numbers directly on the valve cover or on the coil packs, which can remove any guesswork about the front-to-back ordering.
Summary
Cylinder 4 on a 2009 Nissan Versa with the MR18DE engine is the rearmost cylinder, closest to the firewall when viewed from the front of the car. To locate it, start at the front of the engine, count back to the last cylinder, and use the ignition coils or spark plugs as a cross-check. When performing maintenance, verify with the service manual for your exact VIN, and ensure the engine is cool before starting any work.