What Does P2337 Mean?
Cylinder 2 Above Knock Threshold indicates the ECM has detected excessive detonation on cylinder 2 that persists beyond the maximum knock correction range. The knock sensor system is reporting combustion knock events that the ECM cannot fully suppress through ignition timing retard alone.
Common Causes
30%
Carbon deposits in cylinder 2 combustion chamber raising effective compression
25%
Fuel injector 2 partially clogged or delivering lean mixture
25%
Knock sensor malfunction or wiring issue generating false readings
20%
Inadequate fuel octane or contaminated fuel causing detonation
Diagnostic Steps
1
Step 1: Check fuel trim data for bank 1 (or cylinder-specific if available). Long-term fuel trim above +10% suggests a lean condition contributing to knock.
2
Step 2: Compare knock retard values across all cylinders. Isolated knock on cylinder 2 points to a cylinder-specific issue rather than a sensor fault.
3
Step 3: Test fuel injector 2 flow rate and spray pattern using an injector balance test or by swapping with an adjacent injector.
4
Step 4: Check knock sensor resistance (typically 100K-500K ohms) and inspect wiring for damage or improper routing.
5
Step 5: Perform a combustion chamber decarbonization if compression test shows elevated values or borescope reveals heavy deposits.
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
Cylinder 2 Above Knock Threshold indicates the ECM has detected excessive detonation on cylinder 2 that persists beyond the maximum knock correction range. The knock sensor system is reporting combustion knock events that the ECM cannot fully suppress through ignition timing retard alone.
The most common cause of P2337 (Cylinder 2 Above Knock Threshold) is: Carbon deposits in cylinder 2 combustion chamber raising effective compression
Typical repair costs for P2337 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Sustained knock causes cumulative engine damage. Reduce load and speed, avoid aggressive driving, and diagnose promptly to prevent piston or rod bearing failure.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P2337 to identify the root cause.
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Quick Info
Category
Powertrain
System
Ignition/Combustion System
Difficulty
Type
Generic (SAE)
Recommended Tools
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