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.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSSATURN1998SL2 L4-1.9L DOHC VIN 7REPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSKNOCK SENSORDESCRIPTION AND OPERATION
1998 Saturn SL2 L4-1.9L DOHC VIN 7
Knock Sensor: Description and Operation
1998 Saturn SL2 L4-1.9L DOHC VIN 7SECTION Description and Operation
DESCRIPTION
The knock censor circuit consists of a knock sensor, circuit 496 and the PCM. The sensor is mounted in the back of the engine near the top of the block and is used to detect abnormal vibration (spark knocking). Within the engine block, the sensor produces an A/C output voltage which increases with the severity of the knock. The PCM will retard timing to a maximum correction based on the signal it receives from the knock sensor.
OPERATION
The PCM will learn a minimum noise level at idle from the knock sensor and compare level at around 1500-3500 rpm. If the PCM sees no change in noise a DTC P0327 will set after an elapsed time. If the PCM cannot control knock whereas the sensor has detected too much noise due to an excessively noisy engine, a DTC P0326 will set.
The PCM will automatically retard spark to a value that corrected a knock problem previously if it exists again in that ignition cycle. The PCM however, will always try to work back to a zero compensation or no retard.
The knock sensor signal is only used during the TDC combustion event, which is determined by the 7x signal (knock window).
The knock censor circuit consists of a knock sensor, circuit 496 and the PCM. The sensor is mounted in the back of the engine near the top of the block and is used to detect abnormal vibration (spark knocking). Within the engine block, the sensor produces an A/C output voltage which increases with the severity of the knock. The PCM will retard timing to a maximum correction based on the signal it receives from the knock sensor.
OPERATION
The PCM will learn a minimum noise level at idle from the knock sensor and compare level at around 1500-3500 rpm. If the PCM sees no change in noise a DTC P0327 will set after an elapsed time. If the PCM cannot control knock whereas the sensor has detected too much noise due to an excessively noisy engine, a DTC P0326 will set.
The PCM will automatically retard spark to a value that corrected a knock problem previously if it exists again in that ignition cycle. The PCM however, will always try to work back to a zero compensation or no retard.
The knock sensor signal is only used during the TDC combustion event, which is determined by the 7x signal (knock window).
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
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.