The P0201 code on your 2021 Honda Civic points to a specific problem with the cylinder 1 fuel injector circuit. This precise identification makes diagnosis more straightforward than generic injector codes, directing attention to one specific component.
Cylinder 1 Location on the Civic
On the 2021 Civic's 2.0L four-cylinder engine, cylinder 1 is the first cylinder at the timing belt/chain end of the engine—typically the passenger side when facing the engine. The injector connector is accessible from the top of the engine after removing the engine cover.
What Causes P0201
The code sets when the ECM detects an abnormality in the cylinder 1 injector circuit—this could be an open circuit (broken wire or disconnected injector), short to ground, short to power, or the injector coil itself has failed. Internal injector failure causing abnormal current draw also triggers this code.
Step-by-Step Diagnosis
Begin with a visual inspection of the cylinder 1 injector connector—look for damage, corrosion, or disconnection. Measure injector resistance with an ohmmeter (compare to spec, typically 10-15 ohms). Test for voltage at the connector with key on. Swap the cylinder 1 injector with another cylinder—if the code follows the injector, replacement is needed.
Repair and Verification
If the injector tests bad, replacement is straightforward on the Civic. The intake manifold doesn't require removal. Install a new O-ring with the replacement injector. If wiring is damaged, repair and protect against future chafing. Clear codes and verify no return after multiple drive cycles.