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1995 Olds 98 P0325 Knock Sensor Code: Diagnosis and Troubleshooting

Model: 95 olds 98 Fault Code: P0325 Posted: 2015-08-30 18:45

I own a 1995 Oldsmobile 98 with a persistent P0325 diagnostic trouble code. I've checked the knock sensor wiring and confirmed it's showing proper resistance (5 volts, low ohms) — all connections appear intact. I also replaced the engine control module (ECM) with a new one, but the code persists. What other potential causes could be responsible for this issue? The vehicle runs normally with no noticeable knocking sounds or exhaust leaks.

Related fault codes
P0325
Comments (4)
Anonymous 2015-08-31 11:09

This is a 1995 model — that means it's likely equipped with OBD I or OBD 1.5, not OBD II. The 8th character of the VIN would help confirm which system is in use. BASICS: - The knock sensor generates an AC voltage signal when engine knocking occurs. - Is your engine running quietly? Are there any ticking noises, knocks, or exhaust leaks? - Is the sensor housing properly grounded? Sealant buildup could interfere with grounding. - Are there any other wires running close to the knock sensor harness? Interference can cause false readings. - A faulty alternator diode may create high AC voltage signals that mimic a knock condition and trigger P0325.

Anonymous 2015-08-31 20:11

The vehicle uses an OBD 1.5 system, which is relatively rare today.

Anonymous 2015-08-31 20:16

No visible exhaust leaks or wires near the sensor. I've checked everything thoroughly — I'm a technician with over 30 years of experience, but this issue has stumped me completely. Any additional insights or diagnostic steps would be greatly appreciated.

Anonymous 2015-09-01 08:38

You're using an OBD 1.5 scanner, which is uncommon. If you haven't worked directly with the knock sensor system, check for AC diode leakage in the wiring harness — this can cause false signals that trigger P0325. Given it's a 1995 model, I'm not fully certain about the full knock control system (e.g., knock module or logic circuit). If time permits, I'll review the specific troubleshooting tree for this vehicle.