Comprehensive diagnostic guide for OBD-II code P1333 CKP-CMP correlation fault

What This Code Means

• P1333 is widely treated in standard code lists as a crankshaft position (CKP) to camshaft position (CMP) correlation fault. In practice, the ECU expects a consistent and timely relationship between the CKP sensor signal and the CMP sensor signal; if the signals fall out of expected synchronization beyond limits, the P1333 trouble code sets.
• The specific definition can vary by vehicle family (OEM), and a given vehicle may interpret P1333 slightly differently. For standard code interpretation, see GitHub definitions for P1333; for general OBD-II context, see the OBD-II diagnostic trouble code sections in Wikipedia (Powertrain Codes and CKP/CMP related issues).

Symptoms reported by drivers (real-world complaints informing symptom descriptions)

• The engine cranks but does not start or runs very poorly, especially if the CKP-CMP correlation is lost during cranking.
• Intermittent no-start or stalling, particularly after hot restarts or during sustained highway driving that requires stable ignition timing.
• Rough idle, misfires, or bucking under load as the ECU loses synchronization between CKP and CMP signals.
• MIL illumination with P1333 stored; on some vehicles, the MIL may come on during an event when the correlation fault is detected.
• In some cases, the problem is intermittent and the vehicle starts normally after a few attempts or after disconnecting/reconnecting sensors (symptom timing can vary by vehicle).

Why this matters

• The CKP and CMP sensors generate critical timing information used by the ECU to control ignition and fuel timing. An out-of-range correlation often points to one of several root causes (sensor, wiring, or mechanical timing) rather than a simple fault, and the diagnostic approach must verify both electrical signals and mechanical timing.

Cause Probability

• CKP sensor fault (signal noise, open circuit, degraded reluctor, misalignment): 40-60%
• CMP sensor fault or CMP/CKP correlation issue (sensor wiring, sensor alignment, reference voltage issues): 20-30%
• Wiring harness/connectors, shorts to ground or 5V, poor grounds: 10-20%
• Mechanical timing issue (timing belt/chain wear, stretched chain, stretched belt, slipped teeth, timing marks out of alignment): 5-15%
• PCM/ECU fault or failed relearn/adaptation (less common; varies by vehicle): 0-5%
  Note: These ranges reflect common ASE diagnostic experience with CKP/CMP correlation scenarios and are not a substitute for OEM- or model-specific data.

Diagnostic Approach

Begin with safe, non-destructive checks and move toward more invasive or time-consuming tests.

1) Confirm the fault and gather context

• Verify the DTC is still present with a scan tool; capture freeze-frame data (engine RPM, registered faults, engine load, coolant temp, misfire counts if available).
• Check for related codes that frequently accompany CKP/CMP issues (examples: P0335 CKP Sensor A Circuit, P0336 CKP Sensor A Circuit Range/Performance, P0340 CMP Sensor A Circuit, P0345 CMP Sensor A Circuit Range/Performance). The presence of related CKP/CMP codes strengthens a correlation fault hypothesis.
• Note vehicle-specific notes from OEM service manuals if available (some engines require a specific relearn or adaptation after sensor replacement).

2) Visual and mechanical inspection

• Inspect CKP and CMP sensors and their wiring harnesses for obvious damage, corrosion, or loose connections. Look for oil leaks, wiring chafing, and connector oxidation.
• Check grounds and the 5V reference supply to CKP/CMP sensors if accessible with a multimeter or oscilloscope.
• Inspect the timing system (timing belt/chain, tensioners, guides) and verify timing marks are within spec for the engine. A slipped timing belt/chain or worn tensioner can cause a loss of proper CKP-CMP synchronization.

3) Electrical/signal inspection (preferred with scope)

• Using a digital multimeter and/or an oscilloscope, verify:
  • CKP sensor supply and ground integrity (often 5V reference; check for stable supply and solid ground).
  • CMP sensor supply and ground integrity similarly.
  • Relative signal integrity: observe CKP and CMP waveform shapes during cranking and, if possible, running. Ensure the CKP and CMP signals are present and switching cleanly without excessive noise.
  • Correlation check: as the engine crankshaft turns, do CKP and CMP signals maintain a consistent, synchronized phase relationship? A mismatch or lack of correlation is consistent with P1333.
• If a related P0335/P0340/P0345 code is present, perform the appropriate sensor circuit checks first (these codes indicate CKP/CMP circuit issues and can help prioritize the diagnostic sequence).

4) Sensor and circuit tests

• Check CKP and CMP sensor resistance if applicable. Some CKP/CMP sensors are active (3-wire) and require specific resistance checks or reference voltage checks.
• Inspect for shorts to 12V, open circuits, or parasitic currents. Verify that the 5V reference is present and that sensor grounds are solid.
• For a suspected sensor fault, swap with a known-good sensor if possible, or swap the suspect sensor with a known-good unit (when feasible) to confirm the fault. Some vehicles will require a relearn/adaptation after sensor replacement.

5) Mechanical timing checks (if electrical tests are inconclusive)

• If timing marks indicate misalignment or a mechanical fault, correct timing alignment according to the service manual.
• If a timing chain/belt issue is suspected (slack, jumped teeth), rectify as needed. In some engines, belt/chain issues are not user-serviceable and require a professional repair.
• After re-timing, re-check CKP/CMP correlation to ensure outputs are synchronized.

6) ECU relearn/adaptation and functional verification

• Some vehicles require a PCM relearn, synchronization, or crank/cam adaptation procedure after sensor replacement or timing repair. Follow the OEM procedure if available.
• Clear the DTCs and perform a controlled engine start and drive cycle to observe whether the code reappears. Monitor CKP/CMP signals during cranking and running to verify continued correlation.

7) Post-repair verification

• Perform a complete drive cycle that covers cold start, warm-up, idle, acceleration, holding rpm, and deceleration to ensure there are no repeating issues.
• Confirm no misfire, no no-start conditions, and that the MIL remains off.
• If P1333 reappears, revisit the signal integrity and timing-related possibilities, and consider mechanical timing or sensor replacement again if warranted.

Repair/replacement options (aligned with probable causes)

• CKP sensor: replace with OEM-specified sensor, ensure proper torque and connector integrity; inspect wiring harness for damage.
• CMP sensor: replace if testing indicates fault; verify sensor alignment and replacement affects signal correlation.
• Wiring and grounds: repair or replace damaged harness sections; clean and reseat connectors; fix ground straps to ensure solid ground.
• Mechanical timing: replace timing belt/chain, tensioner, guides as needed; verify timing alignment after installation.
• ECU: in rare cases, update or reflash could be necessary if a known defect affects timing correlation in a specific vehicle family.
  Note: Always consult OEM service information for torque specs, timing procedures, and relearn requirements. The general approach above is consistent with standard CKP/CMP correlation fault handling described in the OBD-II context.

Safety Considerations

• De-energize the ignition and disconnect the battery when performing wiring repairs in order to avoid electrical shock or short circuits.
• When working around timing components, follow all safety procedures to avoid injury or engine damage. If you suspect a timing-related issue, avoid cranking the engine aggressively after patient inspection to prevent valve damage in interference engines.
• Use appropriate PPE and ensure the vehicle is securely supported when inspecting or removing components.

Documentation and references (for further reading)

• OBD-II uses standardized diagnostic trouble codes (DTCs) and that powertrain codes cover engine and emission-related issues. It describes the general framework for CKP/CMP correlation concerns and their impact on engine timing and synchronization.
• GitHub definitions provide a standard interpretation of P1333 as a CKP-CMP correlation fault, and they are commonly used as a reference for code definitions in diagnostic tooling and documentation.

Practical Tips

• Document all waveforms and sensor readings (screenshots or data logs) when diagnosing CKP/CMP correlation issues; this helps in demonstrating the exact fault condition if the problem is intermittent.
• If the vehicle has a known history of timing chain/belt wear or a high-mileage engine, consider mechanical timing as a higher-probability cause, even if electrical symptoms exist.
• Always verify related codes (P0335, P0340, P0345, etc.) to build a robust hypothesis about the root cause.

Summary

• P1333 is a CKP-CMP correlation fault indicating the ECU detected a loss of synchronization between crankshaft position and camshaft position signals. Start with sensor wiring, signal quality, and sensor health, then verify timing and mechanical integrity if needed. Use a systematic approach, consult OEM procedures for relearn/adaptation when applicable, and validate results with a controlled drive cycle after repairs.

This diagnostic guide was generated using verified reference data:

• Wikipedia Technical Articles: OBD-II

Content synthesized from these sources to provide accurate, real-world diagnostic guidance.

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