|Trouble Code||Fault Location||Probable Cause|
|P1337||Crankshaft Position Sensor 2 No Signal (ACURA, HONDA)
Camshaft Position Sensor Bank 1 Short To Ground (AUDI, VOLKSWAGEN)
#7 MF Signal Line Short (HYUNDAI)
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What Does Code P1337 Mean?
OBD II fault code P1337 is a manufacturer specific code that is defined by car maker Honda as “Crankshaft Position Sensor 2 No Signal”, or sometimes as “Engine Speed (RPM) Fluctuation Sensor No Signal”, and is set when the PCM (Powertrain Control Module) fails to detect a signal from the crankshaft position sensor.
While the primary purpose of a crankshaft position sensor is to generate ignition trigger signals that are converted into ignition sparks by the ignition system and injector impulses by the fuel injection system, it also has another, equally critical task. This secondary task is to detect misfires through the small variations in the rotational speed of the crankshaft that are produced by misfires, hence the reference to engine speed fluctuations in the alternative definition.
In terms of operating principles, crankshaft sensors are typically of the Hall-effect type that generates ON/OFF signals when the teeth in a rotating reluctor ring pass in front of the sensing element in the sensor. This is similar to how wheel speed sensors work, but in the case of crankshaft position sensors, the reluctor ring that works in conjunction with the sensor has a gap between two teeth that is double the distance between all other teeth.
As the reluctor ring rotates, this gap crates a signal that is markedly different from the signals created by other teeth, and the PCM uses this unique signal as a reference point on which to base an ignition spark and fuel injector pulse for cylinder #1. All other ignition sparks and injector pulses are calculated both from this point onwards in the direction of rotation, and by an algorithm that counts the individual signals the sensor/reluctor ring generate.
However, depending on the number of teeth on the reluctor ring, the PCM may use every signal to generate ignition sparks and injector pulses. On some systems however, the PCM may count all the signals generated in every two engine revolutions, and then divide this number by a preprogrammed number to calculate the exact moment when to deliver sparks and injection pulses to each individual cylinder, regardless of the engine speed at any given moment.
If there are no misfires present, even misfires that are not detectable except through diagnostic equipment, the engine will rotate at a constant speed. However, even minute imbalances in compression pressure, injected fuel volumes, or the intensity of ignition sparks between cylinders can produce small variations in the crankshaft’s rotational speed, which will in turn, produce small variations in the frequency of the ON/OFF signals generated by the crankshaft position sensor.
If such a variation exceeds a typical value of about 2% of the crankshaft’s speed during one engine cycle, the PCM will recognize that a misfire is present, and will set an appropriate misfire code and illuminate warning light as a result. If however, the PCM fails to detect any signal from the crankshaft position sensor during cranking (i.e., before the engine starts), it will recognize that it cannot produce ignition sparks and fuel injector pulses, and it will set code P1337 (and possibly illuminate a warning light) as a result.
Where is the P1337 sensor located?
The image above shows the location (circled) of the crankshaft position sensor on a 2009 Honda Civic engine. Note though that on many later models that use timing belts, the sensor was moved to a location behind the timing cover, which means that several major engine components must be removed, or partially disassembled to gain access to the crankshaft position sensor. It is therefore recommended that a reliable source of service information be consulted to locate and identify crankshaft position sensors on Honda applications correctly, since in many cases, a dedicated sensor that monitors the TDC (Top Dead Center) position of cylinder #1 is located close to the crankshaft position sensor.
What are the common causes of code P1337?
Common causes of code P1337 could include one or more of the following-
- Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors in the crankshaft position sensor’s wiring harness
- Incorrect adjustment of the crankshaft position sensor, but note that this only applies to sensors that are adjustable
- Damaged or defective crankshaft position sensor
- Use of some aftermarket crankshaft position sensor
- Failed or failing PCM, but note that since this is a rare event, the fault must be sought elsewhere before any control module is replaced
What are the symptoms of code P1337?
Symptoms of code P1337 are much the same across all applications, and could include the following-
- Stored trouble code and illuminated warning light
- In some cases, multiple additional codes may also be present
- Engine will crank, but will not start
Other Manufacturer Specific Definitions for P1337Camshaft position (CMP) sensor, short to ground (Volkswagen)
Crankshaft position (CKP) circuit malfunction (Acura)
Camshaft position (CMP) sensor, Bank 1 - short to ground (Audi)
CSF Sensor No Signal (Honda)
#7 MF Signal Line Short (Hyundai)
Engine control module (ECM), RPM signal – output (Mercedes-Benz)