OBD Code P1336: Crank/Cam Variation Relearn Needed (GM)

If your GM vehicle has triggered the P1336 diagnostic trouble code, your engine’s computer has detected that it cannot properly synchronize the crankshaft and camshaft timing signals. This code is specific to General Motors vehicles and relates to the ignition system’s ability to precisely time fuel injection and spark events. While not an immediate emergency, this fault should be addressed promptly to restore optimal engine performance and fuel efficiency.

What Does P1336 Mean?

P1336 is a manufacturer-specific code used by General Motors that translates to “Crank/Cam Variation Relearn Needed.” The code indicates that the engine control module (ECM) has lost or cannot establish its learned values for the relationship between the crankshaft position sensor (CKP) and camshaft position sensor (CMP) signals.

Modern GM engines use variable valve timing (VVT) systems that adjust camshaft position to optimize engine performance across different operating conditions. The ECM learns the precise timing relationship between the crank and cam during normal operation. When this learned data is lost or becomes invalid, the P1336 code is set, and the vehicle may enter a “limp mode” until the relearn procedure is completed.

This is different from hard fault codes—P1336 is essentially the ECM asking for a “refresh” of its timing calibration data. It’s a common occurrence after battery disconnection, ECM replacement, or software updates.

Common Symptoms

• Check Engine Light: Illumination of the MIL (malfunction indicator lamp) on the dashboard
• Rough Idle: Engine may run rough or unstable at stops and low speeds
• Reduced Power: Noticeable loss of acceleration and engine power
• Poor Fuel Economy: Decreased miles per gallon due to inefficient fuel injection timing
• Difficulty Starting: Engine may be slow to crank or hesitate during cold starts
• Hesitation During Acceleration: Stumbling or delayed response when pressing the gas pedal
• No Symptoms: In some cases, the vehicle may run normally despite the code being set

Possible Causes

1. Dead or Disconnected Battery (Most Common): Removing the battery or allowing it to fully discharge erases the ECM’s learned timing values. This is the #1 cause of P1336.
2. ECM Reprogramming or Software Update: Reflashing the engine control module clears learned data and requires a relearn cycle.
3. ECM Replacement: A new or remanufactured ECM has no learned values and must complete a relearn procedure.
4. Faulty Crankshaft Position Sensor (CKP): A failing or intermittent CKP sensor prevents accurate crank signal reading, disrupting the crank/cam relationship.
5. Faulty Camshaft Position Sensor (CMP): A malfunctioning CMP sensor causes the ECM to lose synchronization with cam timing.
6. Timing Chain or Belt Issues: Stretched or damaged timing chains can alter the actual relationship between crank and cam positions.
7. Variable Valve Timing (VVT) Solenoid Malfunction: A stuck or failing VVT solenoid prevents proper cam timing adjustment.
8. Engine Oil Issues: Low oil level or dirty oil can affect VVT solenoid operation and sensor accuracy.
9. Wiring or Connector Problems: Corroded, loose, or damaged wiring to CKP or CMP sensors disrupts signal transmission.
10. Timing Cover Leaks: Oil leaks around the timing cover can allow moisture to contaminate sensors.

Diagnostic Steps

Step 1: Scan for Additional Codes

Connect a diagnostic scanner to your vehicle’s OBD-II port and retrieve all stored and pending codes. Look for related codes such as P0016 (Crankshaft/Camshaft Position Correlation), P0017, P0335 (Crankshaft Position Sensor), or P0340 (Camshaft Position Sensor). These codes may indicate the root cause.

Step 2: Check Battery and Electrical Connections

Verify that the battery is fully charged (12.6V or higher) and that all battery terminals are clean and tight. Check the condition of the battery cable connections. If the battery was recently disconnected or replaced, this is likely the cause of P1336.

Step 3: Inspect Sensor Connectors

Locate the crankshaft position sensor (typically near the crankshaft pulley) and camshaft position sensor (usually on the cylinder head). Inspect both connectors for corrosion, looseness, or damage. Disconnect and reconnect each connector firmly to ensure good contact.

Step 4: Check Engine Oil Level and Condition

Low oil level or dirty oil can affect VVT system operation. Check the dipstick and top off if necessary. If the oil is dark or overdue for a change, perform an oil and filter change.

Step 5: Clear the Code and Perform a Relearn Procedure

Use a diagnostic scanner to clear the P1336 code. Then, follow the manufacturer’s relearn procedure for your specific GM vehicle model. Most GM relearn procedures involve:

• Starting the engine and allowing it to reach operating temperature
• Driving the vehicle at varying speeds and loads for 10-20 minutes
• Allowing the ECM to complete its learning cycle

Consult your vehicle’s service manual or a GM technical database for the exact relearn steps for your model year and engine.

Step 6: Test Drive and Monitor

After clearing the code and completing the relearn procedure, take the vehicle for a 20-30 minute test drive under normal conditions. Monitor for code recurrence using your scanner. If the code returns, proceed to the next steps.

Step 7: Test Crankshaft Position Sensor

If the code persists, use a multimeter to test the CKP sensor resistance and voltage output. Compare readings to manufacturer specifications. A faulty sensor should be replaced.

Step 8: Test Camshaft Position Sensor

Similarly, test the CMP sensor with a multimeter. Check for proper voltage output and resistance values. Replace if readings are out of specification.

Step 9: Inspect Timing Chain and VVT System

If sensors test good, the issue may be mechanical. Have a technician inspect the timing chain for stretching or damage and check VVT solenoid operation. This may require removal of the timing cover.

Repair Cost Estimates

The cost to repair a P1336 code varies widely depending on the underlying cause:

• Code Clear and Relearn Only: $0-$100 (DIY or quick shop visit) — if the code was caused by battery disconnection
• Crankshaft Position Sensor Replacement: $150-$400 (parts and labor)
• Camshaft Position Sensor Replacement: $150-$400 (parts and labor)
• VVT Solenoid Replacement: $200-$600 (parts and labor)
• Oil Change: $30-$75 (if oil condition is the issue)
• Timing Chain Replacement: $1,000-$2,500+ (major repair requiring engine disassembly)
• ECM Reprogramming: $300-$800 (if ECM software update is needed)

Most P1336 codes are resolved with a simple code clear and relearn cycle, costing little to nothing. However, if sensor replacement is needed, expect to pay $150-$400 per sensor.

Can I Still Drive?

Severity: Moderate

In most cases, you can continue driving with a P1336 code, but with caution. The vehicle will typically operate in a reduced-power or “limp mode” to protect the engine until the relearn procedure is completed. Here’s what to expect:

• Safe to Drive Short Distances: You can drive to a repair shop or auto parts store to have the code cleared and relearned.
• Reduced Performance: Expect rough idle, hesitation, and poor fuel economy while the code is active.
• Not Safe for Highway Driving: Avoid long highway trips or heavy acceleration until the issue is resolved.
• Risk of Stalling: In rare cases, the engine may stall at stops if the relearn process is severely disrupted.
• No Immediate Engine Damage: P1336 itself does not cause engine damage, but underlying sensor or timing issues could if left unaddressed.

The safest approach is to address the code as soon as possible. If you recently had your battery disconnected or replaced, simply clearing the code and allowing the vehicle to complete a relearn cycle (via normal driving) will likely resolve the issue within a day or two.

Frequently Asked Questions

Q: Will clearing the P1336 code fix the problem?

A: Clearing the code alone may not permanently fix the issue if there’s an underlying sensor or mechanical problem. However, if the code was caused by battery disconnection or ECM reprogramming, clearing the code and performing a relearn procedure will resolve it. If the code returns after clearing, there’s likely a faulty sensor or other component that needs replacement.

Q: How long does the crank/cam relearn procedure take?

A: The relearn procedure typically takes 10-30 minutes of driving at varying speeds and loads. Some GM vehicles may require additional time. After clearing the code, allow the vehicle to complete at least one full driving cycle (start, drive, and shut off) before checking if the code returns.

Q: Can I clear the P1336 code myself?

A: Yes, you can clear the code yourself using an OBD-II scanner (available at auto parts stores for $25-$100). However, you’ll still need to perform the relearn procedure, which typically involves driving the vehicle under specific conditions. If you’re not comfortable doing this, a technician can handle it in 30 minutes to an hour.

Q: Is P1336 the same as P0016?

A: No, they are different codes. P1336 (GM-specific) indicates that the ECM needs to relearn the crank/cam relationship, while P0016 is a generic code indicating an actual correlation fault between crankshaft and camshaft position. P0016 suggests a real timing problem, whereas P1336 is often just a learning issue. However, if both codes appear together, there may be a genuine timing synchronization problem.

Q: What happens if I ignore the P1336 code?

A: Ignoring the code will result in continued poor performance, rough idle, and reduced fuel economy. The vehicle may also fail an emissions test. More importantly, if the code is caused by a faulty sensor or timing issue, ignoring it could lead to more serious engine problems over time. It’s best to address it promptly.