The knock sensor in a 2012 Honda Civic is mounted to the engine block on the side toward the firewall, near the back of the engine where the block meets the transmission; it is accessed from the engine bay and connected by a two-pin electrical connector.
In 2012 Civics, most models use the 1.8-liter i-VTEC engine, with a possible 2.0-liter option in some markets. The knock sensor location is generally in the same region—on the engine block’s side facing the firewall—but the exact hole and orientation can vary by engine code (R18A/R18Z1 for 1.8L, or K20 for any larger variants). If you need the precise spot for your exact engine, consult the service manual or confirm the engine code stamped on the block.
1.8L i-VTEC engine (R18/R18Z1) location
The following notes describe the typical KS location for the common 1.8L engine found in 2012 Civics (LX/EX).
- The sensor is mounted into a threaded hole in the side of the engine block, usually toward the rear of the engine near the bellhousing (between the head and the transmission).
- It has a two-pin electrical connector that runs to the engine wiring harness; the plug is often tucked under or behind the intake manifold.
- On many cars, you may need to remove the engine cover or some intake components to clearly see the sensor.
Conclusion: For most 2012 Civics with the 1.8L engine, look along the left (passenger) side of the engine block, toward the back, where the block meets the transmission; the sensor is a small round device with a two-pin connector threaded into the block.
2.0L or alternative engines in some markets
The 2012 Civic lineup in some regions used engines other than the 1.8L, and in those cases the KS location remains on the block but may sit slightly higher or lower depending on the engine orientation and ancillary components. The general rule is: look for a small round sensor with a two-wire harness screwed into the engine block on the side toward the firewall, near the bellhousing.
- On most 2.0L variants, the KS should still be mounted to the engine block's side close to the back, near the transmission.
- The harness routing is similar: a two-pin connector connected to the engine harness behind the intake or near the firewall.
Conclusion: While the exact hole can differ by engine code, the knock sensor on 2012 Civics is located on the engine block near the back toward the firewall; verifying with the service manual for your exact engine code is recommended.
How to access and replace if needed
If you’re inspecting or replacing the knock sensor, prepare for a bit of space in the engine bay. The KS is a threaded sensor; you’ll need the correct size socket and torque specification from the service manual, disconnect the battery, remove obstructing components if necessary, loosen the sensor counterclockwise, and install the new sensor with the recommended torque. Ensure the two-pin connector is clean and reattached securely.
Note: After replacing the sensor, reset or re-learn the ECU per the manual if required for your vehicle.
Summary
The knock sensor on a 2012 Honda Civic is mounted to the engine block on the side toward the firewall, near the back of the engine and close to the transmission. The location is generally consistent across 1.8L models, with minor variations for other engine variants or markets; always verify with the specific engine code in your car’s service manual.