P0027 is an OBD-II trouble code that relates to your engine’s variable valve timing system on the exhaust side. When this code sets, your engine computer has detected that the exhaust valve timing for bank 1 isn’t responding correctly to commands. You might notice rough running, poor fuel economy, or even stalling. While it doesn’t always mean catastrophic damage, ignoring it can lead to bigger problems. In this guide, you’ll learn what P0027 means, common causes, symptoms, and how you or your mechanic can diagnose and fix it properly.
What Does P0027 Mean?
P0027 stands for “Exhaust Valve Control Solenoid Circuit Range/Performance (Bank 1).” In simple terms, your engine control unit (ECU) is trying to adjust the exhaust camshaft timing using an oil-controlled solenoid, but the actual movement or feedback doesn’t match what the ECU expects.
“Bank 1” is the side of the engine that contains cylinder #1. The ECU monitors camshaft position using sensors and compares it to the crankshaft. If the exhaust cam on bank 1 is too advanced, too retarded, or just not responding as commanded, it sets code P0027.
Quick Reference
- Code: P0027
- Definition: Exhaust Valve Control Solenoid Circuit Range/Performance (Bank 1)
- System: Variable Valve Timing (VVT) / Variable Camshaft Timing (VCT)
- Severity: Moderate – can become serious if ignored
- Typical Causes: Low/dirty oil, faulty VVT solenoid, wiring issues, timing problems
Real-World Example / Field Notes
In the shop, I see P0027 most often on higher-mileage engines that haven’t had regular oil changes. For example, a customer with a mid-2000s Subaru came in complaining of poor power and a check engine light. The scan tool showed P0027, and live data revealed the exhaust cam on bank 1 lagging behind the commanded angle. Pulling the VVT solenoid showed heavy sludge buildup. After an oil change, cleaning the solenoid screen, and clearing the code, the engine ran smoother and the code stayed gone. In other cases, I’ve had to replace the solenoid or repair damaged wiring.
Symptoms of P0027
- Check engine light on: The MIL/SES light will usually be illuminated and P0027 stored as a confirmed code.
- Rough idle: You may feel the engine shaking or fluctuating RPM at stoplights due to unstable valve timing.
- Loss of power: Acceleration can feel weak, especially at low or mid-range RPM where VVT is most active.
- Poor fuel economy: Incorrect exhaust valve timing can reduce combustion efficiency and increase fuel use.
- Hard starting or stalling: In more severe cases, the engine may crank longer or stall at idle.
- Engine noise: You might hear ticking or rattling from the timing chain/belt area if timing components are worn.
- Failed emissions test: Incorrect cam timing can raise emissions and cause an inspection failure.
Common Causes of P0027
Most Common Causes
- Low or dirty engine oil: VVT systems rely on clean oil at the correct pressure. Sludge or low oil level can restrict the oil passages to the exhaust cam phaser and solenoid.
- Faulty exhaust VVT solenoid (bank 1): The solenoid that directs oil to the exhaust cam phaser can stick, clog, or fail electrically, causing range/performance issues.
- Clogged oil control passages: Debris or sludge in the VVT oil galleries can delay or block cam movement, triggering P0027.
- Incorrect camshaft timing: A stretched timing chain, worn tensioner, or incorrectly installed timing belt can put the exhaust cam out of the expected range.
- Wiring or connector problems: Corroded, damaged, or loose connectors at the VVT solenoid can cause erratic signals or loss of control.
Less Common Causes
- Faulty camshaft position sensor (exhaust side or shared): If the sensor reads incorrectly, the ECU may think the cam is out of range when it isn’t.
- Faulty crankshaft position sensor: Incorrect crank reference can throw off cam/crank correlation and set timing-related codes.
- Defective cam phaser (exhaust cam gear): Internal wear or sticking in the phaser can prevent it from reaching the commanded position.
- ECU software or internal failure: Rarely, outdated software or a failing ECU driver circuit can mismanage the VVT system.
- Previous engine work errors: Incorrect timing marks during a head gasket, timing belt, or chain job can cause persistent P0027.
Diagnosis: Step-by-Step Guide
To diagnose P0027 correctly, you’ll want a basic scan tool (preferably one that reads live data and Mode $06), a digital multimeter, basic hand tools, and access to service information for your specific vehicle. If you’re not comfortable working around hot engines and oil systems, this is a good job for a professional technician.
- Confirm the code and check for others. Connect your scan tool, read all stored and pending codes, and note any related VVT or cam/crank correlation codes (such as P001x series). Address obvious oil pressure or misfire codes at the same time.
- Check engine oil level and condition. With the engine off and cool, verify the oil is at the correct level and not thick, black, or sludgy. If it’s overdue, change the oil and filter with the correct grade before going deeper.
- Inspect wiring and connectors. Locate the exhaust VVT solenoid on bank 1. Look for broken wires, oil-soaked connectors, corrosion, or loose pins. Gently wiggle the harness while watching live data for any changes.
- Use live data to monitor cam timing. With the engine warm, look at “Exhaust Cam Actual vs Commanded” (names vary by brand). Rev the engine lightly. If the commanded angle changes but the actual angle barely moves or lags, you likely have a VVT control or mechanical issue.
- Test the VVT solenoid electrically. Unplug the solenoid and use a multimeter to check resistance against spec. Then check for proper voltage supply and ground from the ECU with the key on. Any open circuit or short needs to be repaired.
- Check solenoid operation (if accessible). On some engines you can remove the solenoid and visually inspect the screen for debris. You can also bench-test it with a 12V power source to see if it clicks and actuates smoothly.
- Evaluate oil pressure and condition inside the engine. If you suspect low oil pressure, have a mechanic test it with a mechanical gauge. Low base oil pressure can prevent the VVT system from working correctly.
- Inspect timing components if needed. If electrical and oil issues check out, you may need to inspect the timing chain/belt alignment and the exhaust cam phaser. This often requires removing covers and aligning timing marks using service manual procedures.
- Clear codes and perform a road test. After repairs or cleaning, clear P0027 and drive under mixed conditions while monitoring live data. If the exhaust cam now follows the commanded angle and the code doesn’t return, the repair is successful.
Pro tip: On some vehicles, you can use advanced scan tools to run an “actuator test” on the exhaust VVT solenoid. This lets you command the solenoid on and off while watching the cam angle change, which is extremely helpful for pinpointing whether the problem is electrical, hydraulic, or mechanical.
Possible Fixes & Repair Costs
Fixing P0027 can be straightforward or fairly involved, depending on what you find during diagnosis. Common repairs include:
- Engine oil and filter change with the correct viscosity
- Cleaning or replacing the exhaust VVT solenoid on bank 1
- Repairing or replacing damaged wiring/connectors to the solenoid
- Cleaning sludge from VVT oil passages (sometimes with multiple short-interval oil changes)
- Replacing a worn timing chain, tensioner, or cam phaser
- Replacing camshaft or crankshaft position sensors if found faulty
Typical repair costs vary widely. An oil change and solenoid cleaning might run $80–$250. Replacing a VVT solenoid usually falls in the $150–$400 range parts and labor. If timing components or a cam phaser are worn, you could be looking at $600–$1,500 or more, depending on engine design and labor rates. Costs are influenced by vehicle make, engine layout (V6/V8 vs inline), parts availability, and whether additional damage (like heavy sludge) is found.
Can I Still Drive With P0027?
In many cases, you can still drive with P0027 for a short period, especially if the only symptom is a check engine light and mild performance loss. However, it’s not something you should ignore. Incorrect exhaust valve timing can increase fuel consumption, raise emissions, and put extra stress on timing components. If you notice severe symptoms like stalling, loud rattling from the timing area, or very poor power, avoid driving and have the vehicle towed to a shop. When in doubt, treat P0027 as a “drive only to the repair facility” situation.
What Happens If You Ignore P0027?
If you ignore P0027, minor drivability issues can turn into major mechanical problems. Long-term incorrect cam timing can accelerate wear on the timing chain or belt, tensioners, and cam phaser. Sludge buildup may worsen, potentially clogging more oil passages and starving critical components of lubrication. In extreme cases, severe timing issues can lead to valve-to-piston contact on interference engines, resulting in very costly engine damage.
Related Codes
- P0026 – Intake Valve Control Solenoid Circuit Range/Performance Bank 1
- P0019 – Crankshaft Position Camshaft Position Correlation Bank 2 Sensor B
- P0018 – Crankshaft Position Camshaft Position Correlation Bank 2 Sensor A
- P0017 – Crankshaft Position Camshaft Position Correlation Bank 1 Sensor B
- P0016 – Crankshaft Position Camshaft Position Correlation Bank 1 Sensor A
- P0009 – Engine Position System Performance Bank 2
- P0008 – Engine Position System Performance Bank 1
- P0007 – Fuel Shutoff Valve “A” Control Circuit High
- P0006 – Fuel Shutoff Valve “A” Control Circuit Low
- P0005 – Fuel Shutoff Valve “A” Control Circuit/Open
Key Takeaways
- P0027 points to a problem with the exhaust valve control solenoid circuit or VVT performance on bank 1.
- Low or dirty oil and a faulty VVT solenoid are the most common causes, especially on higher-mileage engines.
- Symptoms include a check engine light, rough idle, reduced power, and poor fuel economy.
- Diagnosis should start with oil level/condition, wiring checks, and scan tool data before jumping to major repairs.
- Driving briefly with P0027 is sometimes possible, but delaying repairs can lead to expensive timing or engine damage.
Vehicles Commonly Affected by P0027
P0027 shows up on many makes that use variable valve timing, but it’s especially common on certain models. Subaru flat-four and flat-six engines, various Audi and Volkswagen 2.0T and 3.2/3.6 V6 engines, and some Ford and Mazda engines with VCT systems are frequent visitors in the shop. You’ll also see it on some Hyundai, Kia, and GM vehicles that use oil-controlled cam phasers. Any engine that relies heavily on VVT and has a history of extended oil change intervals is more likely to trigger this code over time.
FAQ
Can P0027 go away on its own?
Sometimes P0027 will clear temporarily if conditions change, like after a cold start or a long highway drive. However, if the underlying issue is dirty oil, a sticky solenoid, or worn timing parts, the code usually comes back. Clearing the code without fixing the root cause is only a short-term bandage.
Is P0027 caused by bad oil?
Bad, dirty, or low oil is one of the most common triggers for P0027. VVT systems need clean oil at the right pressure to move the cam phaser. If you’ve gone far past your oil change interval, starting with a proper oil and filter change using the correct viscosity is a smart first step.
Can a bad camshaft sensor cause P0027?
Yes, a failing camshaft position sensor can contribute to P0027, although it’s not the most common cause. If the sensor sends inaccurate signals, the ECU may think the exhaust cam is out of range. Usually you’ll see additional cam sensor-related codes if the sensor is the main problem.
How serious is P0027 compared to other engine codes?
P0027 is generally considered a moderate-severity code. It’s not as immediately dangerous as a low oil pressure or overheating code, but it’s more serious than a simple EVAP leak. If you ignore it, it can lead to expensive timing and engine repairs, so you should address it as soon as practical.
Can I fix P0027 myself at home?
If you’re comfortable with basic tools and have a decent scan tool, you can handle simple steps like checking oil, inspecting wiring, and even replacing the VVT solenoid on some engines. However, diagnosing timing chain stretch, cam phaser issues, or internal oil pressure problems is best left to a professional with the right equipment and service information.