P0325 on Lexus: How to Diagnose & Fix
Knock Sensor 1 Circuit Malfunction (Bank 1)
1 Lexus model · 1 documented issue · $350-$900 repair
P0325 on Lexus by model: symptoms, diagnosis and fix
On the 1MZ-FE V6 the two knock sensors sit in the valley between the cylinder heads, and their sub-harness bakes there under the intake manifold. The wire insulation hardens and chafes, shorting the signal wire to ground and setting P0325 (knock sensor 1 circuit) and/or P0330 (knock sensor 2 circuit). The ECU responds by pulling timing, so the car runs down on power and mileage with a permanent check engine light. The recurring forum lesson is that the harness - not the sensors - is usually the failed part: owners who replace only the sensors see the code return within days.
Common Symptoms
- Check engine light with P0325 and/or P0330
- Reduced power and sluggish acceleration from retarded timing
- Worse fuel economy
- Codes return shortly after replacing only the knock sensors
How to Fix
Replace both knock sensors AND the knock sensor sub-harness with genuine Toyota parts as a set; the intake manifold has to come off either way, so doing the harness at the same time is nearly free labor. Skipping the sub-harness is the single most common reason the code comes back. If codes persist after both, check the ECU ground straps and the connector pins for corrosion before condemning anything mechanical.
Sources for this issue (3)
P0325 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0325 mean on a Lexus?
P0325 stands for "Knock Sensor 1 Circuit Malfunction (Bank 1)." This code indicates a fault in the knock sensor 1 circuit on Bank 1. The knock sensor listens for the vibrations of detonation (pinging/spark knock) and lets the computer retard ignition timing to protect the engine. When the sensor's signal is missing, out of range, or the circuit is open/shorted, P0325 sets. With knock detection compromised, the computer may run more conservative timing, causing reduced power and slightly lower fuel economy, and the engine is less protected against damaging knock. On Lexus it is documented across 1 model: ES.
What are the most common causes of P0325?
The most common causes of P0325 are: Failed knock sensor, Corroded or loose knock sensor connector, Damaged, open, or shorted sensor wiring, Improperly torqued or loosely mounted sensor, Moisture or corrosion in the connector, Wiring harness chafing near the engine, Faulty PCM/ECM (rare). The specific cause varies by vehicle.
How much does it cost to fix P0325 on a Lexus?
Published repair estimates on Lexus range from $350 to $900 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0325 on a different make?
View P0325 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.