P0325 on a Honda Civic
P0325 means knock Sensor 1 Circuit Malfunction (Bank 1). On the Civic, a few causes come up far more than others.
What P0325 usually means on a Civic
P0325 means the Civic's knock sensor circuit has dropped out, so the ECU cannot hear detonation and pulls timing conservatively as a safeguard. You may notice slightly reduced power or worse fuel economy while the code is active. On Honda engines the sensor itself or its connector/wiring is the usual failure. It is generally a reliability annoyance rather than an urgent hazard, though prolonged running with retarded timing is not ideal.
Most common causes on the Civic
- Failed knock sensor
The sensor itself fails with age and heat cycling on Honda fours, opening the circuit.
- Damaged wiring or connector
The knock-sensor harness runs near the block and chafes or corrodes over time.
- Poor ground or ECU connection
A degraded ground can mimic a bad sensor and set the circuit code.
What P0325 costs to fix on a Civic
The knock sensor sits low on the block, on some Civic engines beneath the intake manifold, so labor can outstrip the modest part cost. Inspect the connector and wiring first - a cheap repair - before buying a sensor. Where the manifold must come off, budget for the added access time.
Year, engine and mileage change the answer. Start a case and Redline weighs these causes against what your car shows, then names the check that would settle it.
Other codes on the Honda Civic
Related symptoms
Honda Civic problems & recalls by year
Based on widely reported patterns for this model; individual causes vary by year, engine and history. Generic P0325 behavior is covered on the main P0325 page. Confirm with a scan tool before buying parts.
P0325 on your Civic?
Every problem becomes a Case. Tell Redline what your Civic is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.