P0024

What Does Code P0024 Mean?

DTC P0024 signifies that the Engine Control Module (ECM), also known as the Powertrain Control Module (PCM), has detected an inconsistency in the commanded versus actual position of the “B” camshaft on Bank 2. Specifically, it indicates that the exhaust camshaft (commonly referred to as “B” camshaft in VVT systems) on the bank of the engine that does not contain cylinder #1 (Bank 2) is either over-advanced beyond its specified operating range or is exhibiting a performance issue that prevents it from achieving or maintaining the desired timing. The ECM constantly monitors the rotational position of the camshafts using Camshaft Position (CMP) sensors and compares this data against crankshaft position (CKP sensor) and the target position commanded by the Variable Valve Timing (VVT) or Variable Camshaft Timing (VCT) system. When the actual position of the exhaust camshaft on Bank 2 is consistently or significantly more advanced than what the ECM has commanded, or if the VVT/VCT system for this camshaft fails to meet its target within a predetermined tolerance and time frame, the P0024 code is triggered. This subsystem is crucial for optimizing valve overlap, improving fuel efficiency, and reducing emissions across various engine speeds and loads.

Common Symptoms

• Illuminated Malfunction Indicator Lamp (MIL) / Check Engine Light
• Reduced engine performance, including sluggish acceleration and decreased horsepower
• Rough or erratic idle, potential stalling
• Increased fuel consumption
• Audible ticking or rattling noise from the engine, particularly at idle or low RPMs, potentially indicating low oil pressure to the VVT actuator or a faulty phaser
• Engine hesitation or misfires under various load conditions
• Difficulty starting the engine (in severe cases where timing is significantly compromised)

What Causes the Code P0024?

• Faulty Variable Valve Timing (VVT) / Variable Camshaft Timing (VCT) solenoid (actuator) for the Bank 2 exhaust camshaft, which may be stuck open, stuck closed, or operating inefficiently.
• Insufficient engine oil pressure or incorrect engine oil viscosity, which directly impacts the hydraulic operation of the VVT/VCT system. Sludged oil or debris can restrict oil flow.
• Clogged or restricted oil passages leading to the Bank 2 exhaust VVT/VCT actuator, often due to oil sludge buildup.
• Faulty Bank 2 exhaust Camshaft Position (CMP) sensor, providing inaccurate feedback to the ECM regarding the camshaft’s actual position.
• Mechanical issues with the VVT/VCT phaser (cam gear) itself, such as internal locking pin failure or wear, preventing proper rotation or locking.
• Stretched timing chain or worn timing chain guides/tensioners on Bank 2, leading to incorrect base camshaft timing.
• Wiring harness issues (chafed, open, shorted, high resistance) or corroded electrical connectors affecting the Bank 2 exhaust VVT solenoid or CMP sensor circuits.
• Internal engine mechanical issues, such as worn camshaft bearings, which could restrict camshaft movement or affect oil pressure in the VVT system.
• A rare but possible internal ECM/PCM fault.

How to Diagnose and Troubleshoot

A systematic diagnostic approach is critical for P0024. Begin by gathering essential data and performing visual inspections before diving into component-level testing:

1. Initial Inspection and Data Collection:
   • Connect an OBD-II scanner to confirm P0024. Check for any other related VVT, CMP, or engine oil pressure codes that might provide additional context.
   • Inspect the engine oil level and condition. Low oil level, incorrect viscosity, or severely contaminated/sludged oil is a frequent cause. Correct oil issues immediately.
   • Visually inspect the wiring harness and electrical connectors for the Bank 2 exhaust VVT/VCT solenoid and CMP sensor. Look for signs of damage, corrosion, fraying, or loose connections.
2. Electrical System Checks (using Digital Multimeter – DMM):
   • VVT Solenoid Circuit Test: Disconnect the Bank 2 exhaust VVT solenoid. Using a DMM, measure the resistance across the solenoid’s terminals. Compare this reading to manufacturer specifications (typically 6-15 ohms). An open circuit (OL) or a short to ground indicates an internal solenoid fault.
   • Power and Ground Supply to VVT Solenoid: With the ignition ON and solenoid disconnected, test for proper voltage supply to the VVT solenoid connector (typically battery voltage) and a good ground signal from the ECM (may be a switched ground or pulse-width modulated signal, requiring a scope for dynamic testing).
   • CMP Sensor Circuit Test: Disconnect the Bank 2 exhaust CMP sensor. Test the power supply (usually 5V or 12V), ground, and signal wires at the connector. Check for continuity of the signal wire back to the ECM.
3. Functional and Live Data Analysis (using OBD-II Scanner):
   • Monitor Live Data: Observe engine RPM, Bank 2 exhaust camshaft actual position, Bank 2 exhaust camshaft desired position, and engine oil pressure (if available) during various engine operating conditions (idle, 2000 RPM, etc.). Look for discrepancies where the actual position deviates significantly from the desired position, or if the actual position reads consistently outside the expected advanced range.
   • Bi-directional Control Test: If the scanner supports bi-directional control, command the Bank 2 exhaust VVT solenoid to various positions (e.g., 0% and 100% duty cycle). Monitor the actual camshaft position PID to see if the camshaft responds and moves smoothly to the commanded positions. Listen for the solenoid clicking during activation.
   • Engine Oil Pressure Verification: If the vehicle has an oil pressure sensor, monitor its readings via live data. If not, consider connecting a mechanical oil pressure gauge to verify actual oil pressure, especially if oil-related issues are suspected.
4. Mechanical System Checks:
   • VVT Solenoid Inspection: If electrical tests pass, remove the Bank 2 exhaust VVT solenoid. Inspect it for debris, sludge, or physical damage. Consider bench testing it by applying 12V and observing plunger movement, ensuring it moves freely.
   • Oil Passage Inspection: After removing the VVT solenoid, use a mirror and light to inspect the oil passages within the cylinder head for any visible clogs or debris.
   • Timing Component Inspection: If all other checks yield no definitive fault, and especially if there are other timing-related codes or symptoms, suspicion should shift to mechanical failure of the VVT phaser itself or timing chain stretch/tensioner failure. This often requires significant engine disassembly to visually inspect the timing chain, guides, tensioners, and the VVT phaser.

Recommended Repairs and Solutions

Based on the diagnostic findings, the following repairs are typically recommended:

1. Engine Oil Service: The most common and often overlooked solution. If the engine oil is low, dirty, or incorrect viscosity, perform an immediate oil and filter change with the manufacturer-specified oil. If severe sludge is present, consider an engine oil flush using an approved product, followed by another oil and filter change after a short operational period.
2. Replace Bank 2 Exhaust VVT/VCT Solenoid: If diagnostic tests confirm the solenoid is faulty (incorrect resistance, no response to bi-directional control, or physically clogged/damaged), replace it. Ensure proper sealing and torque during installation. This is frequently the primary fix for P0024.
3. Replace Bank 2 Exhaust Camshaft Position (CMP) Sensor: If sensor testing indicates an erratic, absent, or incorrect signal, replacement of the CMP sensor is necessary.
4. Clear Clogged Oil Passages: If sludge or debris is restricting oil flow to the VVT actuator, the passages must be cleaned. This may involve removing the VVT actuator and using specialized cleaners or air pressure, though extreme cases may require cylinder head removal for thorough cleaning.
5. Repair Wiring/Connectors: If damaged wiring or corroded connectors are identified in the VVT solenoid or CMP sensor circuits, repair or replace the affected sections to restore proper electrical continuity and signal integrity.
6. Replace VVT/VCT Phaser: If internal mechanical failure of the Bank 2 exhaust VVT phaser is diagnosed (e.g., stuck locking pin, excessive internal wear), the phaser itself must be replaced. This is a more involved repair, often requiring special tools and potentially timing cover removal.
7. Timing Component Replacement: If a stretched timing chain, worn guides, or a failing tensioner is found to be the root cause, these components must be replaced as a set to restore correct camshaft timing.

After any repair, clear the DTCs and perform a thorough test drive through various operating conditions to confirm the repair and ensure the readiness monitors complete without the code returning. Always use OEM or high-quality aftermarket components for VVT system repairs to ensure optimal performance and longevity.