P1345 Code: Crankshaft/Camshaft Correlation – Causes, Symptoms & Fixes

The P1345 diagnostic trouble code is specific to General Motors vehicles and signals a critical timing synchronization problem in your engine’s ignition system. When your vehicle’s onboard diagnostic system detects that the crankshaft and camshaft are not properly correlated—meaning they’re out of sync—it triggers this code. This is a moderate-severity fault that requires prompt attention to prevent engine damage and restore proper vehicle operation.

What Does P1345 Mean?

P1345 stands for “Crankshaft/Camshaft Correlation” and is a manufacturer-specific code used exclusively by General Motors. This code indicates that the engine control module (ECM) has detected a timing mismatch between the crankshaft and camshaft.

Here’s how it works normally: The crankshaft controls the pistons’ up-and-down motion, while the camshaft controls the opening and closing of the intake and exhaust valves. These two components must be precisely synchronized for the engine to run efficiently. The ECM monitors this correlation using signals from the crankshaft position sensor (CKP) and camshaft position sensor (CMP). When these sensors report timing that doesn’t match up—or when the actual mechanical timing is off—the P1345 code is set.

This is different from timing codes on other vehicles because GM uses a specific correlation check between these two components. If the timing is off by even a few degrees, the code will trigger.

Common Symptoms

• Check Engine Light: The primary indicator; the light will illuminate on your dashboard
• Engine Cranks But Won’t Start: The most common symptom; the engine may turn over but fail to ignite
• Rough Idle: If the engine does start, it may run very rough and unstable at idle
• Stalling: The engine may stall shortly after starting or while driving
• Loss of Power: Reduced acceleration and overall engine performance
• Hesitation Under Load: The engine hesitates when accelerating or climbing hills
• Poor Fuel Economy: Noticeable decrease in miles per gallon
• Misfires: You may feel the engine misfiring or hear popping sounds from the exhaust

Possible Causes (Ranked by Likelihood)

1. Faulty Camshaft Position Sensor (CMP) – The most common cause; the sensor may provide inaccurate timing signals to the ECM, causing the correlation check to fail
2. Faulty Crankshaft Position Sensor (CKP) – A malfunctioning CKP sensor can send incorrect timing data, disrupting the correlation
3. Timing Chain Stretched or Worn – Over time, the timing chain can stretch, causing the camshaft to fall out of sync with the crankshaft
4. Timing Chain Tensioner Failure – A weak or failed tensioner cannot maintain proper chain tension, leading to timing drift
5. Timing Chain Misalignment – The timing chain may have jumped a tooth on the sprocket, throwing off the correlation
6. Faulty Timing Chain Guide or Sprocket – Worn guides or sprockets can cause the chain to slip
7. Engine Oil Sludge or Low Oil Level – Poor lubrication can cause the timing chain to wear prematurely or the tensioner to fail
8. ECM Software Issue or Corruption – Rarely, the engine control module itself may have a software glitch
9. Wiring or Connector Issues – Corroded or loose connectors on the CMP or CKP sensors can interrupt signal transmission
10. Improper Engine Assembly or Recent Repair – If the engine was recently worked on, timing components may not be properly aligned

Diagnostic Steps

Follow these steps to diagnose the P1345 code:

Step 1: Scan the Vehicle

Use a quality OBD-II scanner to confirm the P1345 code is present. Check for any additional codes that may provide more clues about the root cause. Record the freeze frame data, which shows engine conditions when the code was triggered.

Step 2: Inspect Engine Oil

Check the engine oil level and condition. Low oil or sludgy oil can cause timing chain wear and sensor issues. If the oil is dark and dirty, perform an oil and filter change.

Step 3: Visually Inspect Sensors and Connectors

Locate the crankshaft position sensor and camshaft position sensor (typically on or near the engine block). Inspect the connectors for corrosion, looseness, or damage. Clean any corroded connectors with electrical contact cleaner. Ensure connectors are fully seated.

Step 4: Test the Camshaft Position Sensor

Using a multimeter or scope, test the CMP sensor’s output voltage while the engine is cranking. Compare the readings to your vehicle’s specifications. A faulty sensor typically shows no signal or an erratic signal.

Step 5: Test the Crankshaft Position Sensor

Similarly, test the CKP sensor output while cranking. This sensor is critical for timing correlation. If it’s not producing a clean signal, it needs replacement.

Step 6: Check Timing Chain Condition

If sensors test okay, the issue likely lies with the timing chain. This requires removing the timing chain cover—a more involved procedure. Look for signs of chain stretch, wear on the sprockets, or a weak tensioner. If the timing chain appears worn, it will need replacement.

Step 7: Verify Timing Alignment

If the engine has been recently serviced, verify that the crankshaft and camshaft are properly aligned to their timing marks. Misalignment during reassembly is a common cause of this code.

Step 8: Clear the Code and Test Drive

After making repairs, clear the code using your scanner and take the vehicle for a test drive. Monitor for code recurrence. If the code returns, further diagnosis is needed.

Repair Cost Estimates

Repair costs for P1345 vary widely depending on the underlying cause:

• Camshaft Position Sensor Replacement: $150–$400 (parts and labor)
• Crankshaft Position Sensor Replacement: $150–$400 (parts and labor)
• Sensor Connector Repair/Cleaning: $50–$150
• Timing Chain Replacement: $800–$2,500+ (major repair; labor-intensive)
• Timing Chain Tensioner Replacement: $300–$800
• Timing Chain Guide Replacement: $400–$1,200
• Full Engine Timing Component Overhaul: $1,500–$3,500+

The wide range reflects differences in vehicle model, engine type, and whether additional components need replacement. A simple sensor replacement is relatively affordable, but timing chain work is expensive due to labor costs.

Can I Still Drive?

Severity: Moderate

You should not drive your vehicle if the P1345 code is active and the engine won’t start or runs very rough. Continuing to drive with this fault can cause:

• Complete engine stalling while driving, creating a safety hazard
• Damage to internal engine components if timing is severely off
• Potential catalytic converter damage from misfires

If the engine starts and runs, you may be able to drive carefully to a repair facility, but do so cautiously. Avoid highway driving and heavy acceleration. The longer you drive with this code active, the greater the risk of secondary damage.

Recommendation: Have the vehicle diagnosed and repaired as soon as possible. Do not ignore this code.

Frequently Asked Questions

Q: Will P1345 go away on its own?

A: No. P1345 is a persistent code that will remain until the underlying cause is fixed. While the code might occasionally clear temporarily if the fault is intermittent, it will return until the root problem is resolved. You must diagnose and repair the issue.

Q: Is P1345 the same as a timing code on other vehicles?

A: P1345 is specific to GM vehicles and checks the correlation between crankshaft and camshaft timing. Other manufacturers use different codes for timing issues (such as P0016 for camshaft/crankshaft correlation on some vehicles). However, the underlying problems are similar: timing misalignment, sensor faults, or timing chain wear.

Q: Can a bad battery cause P1345?

A: Indirectly, yes. A weak battery can cause voltage fluctuations that affect sensor signals, potentially triggering timing-related codes. However, a bad battery is rarely the sole cause of P1345. If you suspect a battery issue, have it tested. If the battery is weak, replace it and retest the vehicle.

Q: What’s the difference between replacing a sensor and replacing the timing chain?

A: Sensor replacement is straightforward and relatively inexpensive ($150–$400). The sensor simply plugs in or bolts on. Timing chain replacement requires removing the timing cover and potentially other engine components, making it labor-intensive and expensive ($800–$2,500+). Always diagnose which component is actually faulty before authorizing expensive repairs.

Q: My Silverado/Sierra/Tahoe has P1345 and won’t start. What should I do?

A: First, do not repeatedly try to start the engine, as this can cause additional damage. Have the vehicle towed to a repair facility or diagnose it yourself if you have the tools. Use a scanner to confirm P1345 and check for other codes. Start with the least expensive fixes: inspect and clean sensor connectors, test the sensors, and check the oil. If sensors are okay, the timing chain likely needs inspection or replacement.