What Does P1324 Mean?
P1324 indicates that knock sensor 4 is producing a signal above the expected maximum voltage. The ECM interprets this as either a sensor malfunction, wiring issue, or excessive engine knock. A high signal causes the ECM to aggressively retard ignition timing, leading to noticeably reduced power output.
Common Causes
30%
Knock sensor 4 internal failure producing spurious high output
25%
Electromagnetic interference affecting the sensor signal wire
20%
Short to power in the knock sensor 4 circuit wiring
15%
Incorrect sensor part installed with wrong sensitivity
10%
Actual mechanical knock from engine bearing or valve train wear
Diagnostic Steps
1
Compare knock sensor 4 signal levels to sensors 1-3 at idle — a significantly higher baseline indicates a fault.
2
Check wiring routing for the sensor 4 circuit to ensure it is not running adjacent to high-voltage ignition wires or the alternator.
3
Disconnect the sensor and measure the signal voltage at the ECM connector — it should read near zero with the sensor disconnected.
4
Confirm the knock sensor part number matches the manufacturer's specification for this engine.
5
Perform a stethoscope check on the engine block near sensor 4 to rule out genuine mechanical knock.
Estimated Repair Cost
$100 - $400
Parts + labor, varies by vehicle and location
P1324 indicates that knock sensor 4 is producing a signal above the expected maximum voltage. The ECM interprets this as either a sensor malfunction, wiring issue, or excessive engine knock. A high signal causes the ECM to aggressively retard ignition timing, leading to noticeably reduced power outp...
The most common cause of P1324 (Knock Sensor 4 Circ. High Input) is: Knock sensor 4 internal failure producing spurious high output
Typical repair costs for P1324 range from $100 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Persistent false high-knock signals degrade engine performance via excessive timing retard. If the ECM adapts by ignoring the sensor, real detonation goes undetected, risking piston, ring, and bearing damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1324 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Knock Detection / Ignition Timing
Difficulty
Type
Manufacturer
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