Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0325: Knock Sensor Circuit Malfunction
2004 Acura 3.5RLSECTION DTC P0325: Knock Sensor Circuit Malfunction
WARNING: This page is about a different car, the 2003 Acura RSX. However, it is still accessible from the selected car via links, so may be relevant.
- Perform ECM/PCM reset procedure. See ECM/PCM RESET PROCEDURE/CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. Start engine and run at 3000 RPM, with no load (in park or neutral), until radiator fan comes on. Allow engine to idle. Increase and hold engine speed at 3000-4000 RPM for at least 60 seconds with no load (in park or neutral).
- If DTC P0325 resets, go to next step. If DTC P0325 does not reset, problem is intermittent. System is functioning properly at this time (a test drive may be necessary). Check for poor connection(s) or loose wire(s) between KS harness connector and Gray ECM/PCM 31-pin "A" harness connector. See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS. Repair as necessary.
- Turn ignition switch off. Disconnect starter sub-harness connector C102, located near front of engine compartment. See Fig 1 . Check for continuity between ground and Gray ECM/PCM 31-pin "A" harness connector terminal No. 9 (Red/Blue wire). See Figure . If continuity is not present, go to next step. If continuity is present, repair short in Red/Blue wire between Gray ECM/PCM 31-pin "A" harness connector terminal No. 9 and starter sub-harness connector C102 terminal No. 7 (terminal No. 5 on S model). See appropriate wiring diagram under ENGINE PERFORMANCE in WIRING DIAGRAMS.
- Connect fused jumper wire between ground and Red/Blue wire at starter sub-harness connector C102 terminal No. 7 (terminal No. 5 on S model). See Fig 1 . Check for continuity between ground and Gray ECM/PCM 31-pin "A" harness connector terminal No. 9 (Red/Blue wire). If continuity is present, go to next step. If continuity is not present, repair open in Red/Blue wire between Gray ECM/PCM 31-pin "A" harness connector terminal No. 9 and starter sub-harness connector C102 terminal No. 7 (terminal No. 5 on S model).
- Check for open or short in Red/Blue wire between starter sub-harness C102 terminal No. 7 (terminal No. 5 on S model) and KS sensor. If no problem is present, substitute a known-good KS and recheck. If DTC P0325 does not reset, replace original KS. If DTC P0325 resets, update ECM/PCM or substitute with known-good ECM/PCM. If symptom goes away, replace original ECM/PCM.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.