what does the code 34 knock sensor in a 1994 nissan altima mean

Asked by Jul 01, 2013 at 10:54 PM about the Nissan Altima

Question type: Maintenance & Repair

where is it and how can it be fixed or replaced

3 Answers


Your knock sensor is like a microphone. It "listens" to the engine and if it "hears" knocking or pinging, like from using low octane fuel, it sends a signal to the computer. The computer then, electronically, retards your ignition timing (causes a later spark on the compression stroke of the piston). This stops the knocking or pinging. The knock sensor is screwed into the block. Usually into the side of the block close to where the block meets the head. Most likely the sensor has failed. The computer tests the sensor, while you're driving by momentarily advancing the ignition timing so the engine will knock. If the computer doesn't "hear" the knock it sets a trouble code and switches on the "check engine" light to alert you to the problem. HTH. -Jim

thank you for your answer

my check engine light has never came on and that is for a turbo type engine. Mine isn't turbo. But thanks for the answer

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