|Trouble Code||Fault Location||Probable Cause|
|P1345||Crankshaft Position (CKP)-Camshaft Position (CMP) Correlation||CKP sensor, distributor/camshaft alignment, mechanical fault|
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What Does Code P1345 Mean?
OBD II fault code P1345 is a code used by General Motors – but more specifically by Chevrolet – that is defined as “Crankshaft Position (CKP)-Camshaft Position (CMP) Correlation”, and is set when the PCM (Powertrain Control Module) on Chevrolet models detects a mismatch (correlation fault) in the input data from the Crankshaft -, and Camshaft Position sensors that exceeds a maximum allowable limit.
NOTE: Note that although code P1345 with the definition “Crankshaft Position (CKP)-Camshaft Position (CMP) Correlation”, is also used by closely related GM products, including Buick, Cadillac, Isuzu, Pontiac, and Saturn, this guide primarily deals with code P1345 as it relates to Chevrolet models.
The primary purpose of the crankshaft position sensor is to supply the PCM with data regarding the position of the crankshaft relative to piston #1, in order for the PCM to be able to deliver a spark to cylinder #1 at exactly the right moment to ignite the air/fuel mixture in the combustion chamber. While design specifics vary somewhat between models, all crankshaft position sensors generate a magnetic field that is interrupted when the teeth on a reluctor ring passes in front of the sensor as the crankshaft rotates.
In simple terms, the PCM counts the number of “ON/OFF” signals, and uses this value to calculate the engine speed, which in turn, is used to make adjustments to the ignition timing. Moreover, the reluctor ring has a spot in which one tooth is “missing”, which creates one signal in every engine revolution that is twice as long as all other signals. This gap in the reluctor ring is a reference point relative to piston #1, which the PCM uses to regulate the ignition timing based on engine speed.
However, the engine also needs fuel delivered to the cylinders at the right time to run; so on most applications, the PCM uses input data from a camshaft position sensor to regulate the fuel injection timing. Note however that camshaft position sensors generally do not use reluctor rings to create a signal. In most cases, the signal is created when a single point on the camshaft passes in front of the sensor as the camshaft rotates.
Regardless of design specifics though, the positions of the crank -, and camshafts have to be in agreement relative to piston #1 if the ignition spark and fuel are both to be delivered at the optimal moment. Since the fuel injection timing is determined by the position of the camshaft(s), fuel might be injected either too late or too early relative to both the position of piston #1, and the opening/closing moments of the valves, even if the crankshaft position sensor is indicating the position of piston #1 correctly. If this occurs, the results can vary from excessive fuel consumption, to excessive smoking from the tail pipe, to loss of power, serious misfires that can result in catalytic converter failure, and in serious cases, to dilution of the engine oil that can cause engine failure.
Thus, to avoid these issues and to simplify the process of engine/fuel management, the PCM is programmed to recognize when the input signals from the crank -, and camshaft position sensors no longer correlate exactly. However, to allow for some variation that occurs as the result of mechanical wear on some components such as timing chains, sprockets, and VVT (Variable Valve Timing) actuators, the PCM will generally not set code P1345 until the correlation failure exceeds about 1.5% to a maximum of 2% of the rotation of the crankshaft.
Where is the P1345 sensor located?
The image above shows the location of the crankshaft position sensor (near the flywheel) on a Chevrolet Cobalt engine. Note however that since the location of this, and camshaft position sensors vary greatly between Chevrolet applications, it is critically important to refer to the manual for the affected application to locate and identify these sensors correctly. Failure to identify sensors correctly can lead to confusion, wasted time, misdiagnoses, and the unnecessary replacement of parts and components.
What are the common causes of code P1345?
NOTE: Be aware that on older Chevrolet engines that still use distributors in the ignition system, the position of the rotor arm in the distributor is an indication of the camshaft position relative to piston #1, since the distributor is gear-driven. On these applications, excessive wear of the drive gears, or incorrect installation of the distributor are both roughly analogous to defective camshaft position sensors on applications that use distributor-less ignition systems.
Nonetheless, some common causes of code P1345 could include the following-
- Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors in wiring that is associated with either, or both the crank -, and camshaft position sensors
- Defective crankshaft position sensor
- Defective, cracked, clogged, damaged, or broken crankshaft-mounted reluctor ring. Note however that on some Chevrolet and closely related applications, the reluctor ring may be located inside the engine
- Excessive mechanical wear in timing components, including timing chains and/or chain guides, chain tensioning devices, timing chain sprockets, and VVT/VCT actuators and/or control solenoids
- Defective camshaft position sensor
- Defective VVT (Variable Valve Timing) actuator(s) (If fitted)
- Defective VVT control solenoid(s)
- Insufficient oil pressure to activate VVT actuator(s)
- Defective, or incorrectly installed distributor (If fitted)
- Failed or failing PCM. Note that this is a rare event, and the fault must therefore be sought elsewhere before any control module is replaced
NOTE 1: Note that if code P1345 is present on GM applications with VVT (Variable Valve Timing) and/or VCT (Variable Camshaft Timing), defects in these systems can cause P1345 to set. However, since defects in these systems will almost certainly be indicated by dedicated codes other than P1345, all additional codes must be resolved in the order in which they were stored if a misdiagnosis is to be avoided.
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