What Does P1337 Mean?
P1337 indicates a complete absence of signal from the crankshaft speed fluctuation sensor. This sensor provides fine-resolution crankshaft speed data used by the ECU for misfire detection and combustion quality monitoring. Without this signal, the ECU cannot reliably detect misfires and may disable misfire monitoring entirely.
Safety Warning
Without the crankshaft speed fluctuation signal, the ECU cannot detect misfires, which means catalytic converter damage from unburned fuel may go undetected. Address promptly to protect emission components.
Common Causes
35%
Failed crankshaft speed fluctuation sensor
25%
Open circuit in the sensor wiring harness
20%
Disconnected or damaged sensor connector
12%
Damaged reluctor ring or tone wheel segment
8%
ECU input circuit failure for the fluctuation sensor channel
Diagnostic Steps
1
Verify the sensor connector is fully seated and locked. Check for connector damage, corrosion, or displaced terminal pins.
2
Measure sensor resistance and compare to manufacturer specifications. An open reading indicates internal sensor failure.
3
Check for voltage supply and ground at the sensor connector (if it is an active/Hall-effect type sensor). Verify reference voltage is present.
4
Inspect the wiring harness for open circuits using a continuity test from the ECU connector to the sensor connector on each wire.
5
If wiring and sensor are good, inspect the reluctor ring for damage. Some vehicles use a separate tone wheel for the fluctuation sensor distinct from the main CKP reluctor.
Estimated Repair Cost
$100 - $400
Parts + labor, varies by vehicle and location
P1337 indicates a complete absence of signal from the crankshaft speed fluctuation sensor. This sensor provides fine-resolution crankshaft speed data used by the ECU for misfire detection and combustion quality monitoring. Without this signal, the ECU cannot reliably detect misfires and may disable ...
The most common cause of P1337 (Crankshaft Speed Fluctuation Sensor No Signal) is: Failed crankshaft speed fluctuation sensor
Typical repair costs for P1337 range from $100 to $400, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Without the crankshaft speed fluctuation signal, the ECU cannot detect misfires, which means catalytic converter damage from unburned fuel may go undetected. Address promptly to protect emission components.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P1337 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Position Sensing / Misfire Detection
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