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.
1994 Geo Prizm Base, AutomaticFACTORY OEM SERVICE PROCEDURE
Knock Sensor (LSi)
- A malfunction in the knock sensor circuit will set diagnostic trouble Code 52. For testing procedures, see TESTS W/CODES article in this section. Use the following procedure to diagnose knock sensor.
- Check knock sensor resistance using ohmmeter. Measure resistance between knock sensor terminal and ground. Knock sensor, located on rear of engine block, has Black wire connector. Replace sensor if resistance is not one megohm or higher.
- To check knock sensor operation, remove connector from knock sensor. Connect DVOM between knock sensor terminal and ground. Adjust voltmeter to 200 millivolts on AC scale. Tap on engine block near knock sensor, and note reading. Replace knock sensor if no reading is obtained.
Factory Service Tools
Use the Manual With the Right Hardware
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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.