P0366 – Camshaft Position Sensor “B” Circuit Range/Performance Bank 1

P0366 is one of those camshaft sensor codes that can be confusing when you first see it on your scanner. It sounds serious, and it can be, but with a bit of understanding you can decide whether it’s something to tackle yourself or hand off to a shop. This code deals with the camshaft position sensor “B” on Bank 1 and the signal the ECU is seeing. In this guide, you’ll learn what P0366 means, the most common causes, symptoms, diagnosis steps, and realistic repair costs.

What Does P0366 Mean?

P0366 is an OBD-II diagnostic trouble code that stands for “Camshaft Position Sensor ‘B’ Circuit Range/Performance (Bank 1).” In plain language, your engine computer (ECU) is not happy with the signal it’s getting from the camshaft position sensor “B” on the side of the engine that contains cylinder #1 (Bank 1).

The ECU constantly compares the camshaft signal to the crankshaft sensor signal. When the cam signal is out of expected range, erratic, late, or missing for a certain amount of time, it stores P0366 and usually turns on the check engine light. This can affect ignition timing, fuel injection timing, and variable valve timing operation.

Quick Reference

• Code: P0366
• Definition: Camshaft Position Sensor “B” Circuit Range/Performance (Bank 1)
• System: Engine / Camshaft position sensing
• Severity: Moderate to high (driveability and starting issues possible)
• Typical Fixes: Sensor replacement, wiring repair, timing inspection, reluctor/trigger repair

Real-World Example / Field Notes

In the shop, I often see P0366 on higher-mileage engines with variable valve timing. A common pattern is a car that starts fine cold, but once hot it misfires lightly at idle and occasionally stalls at stoplights. The owner usually says, “It runs okay on the highway, just rough at idle and the light is on.” Scan data will show the camshaft “B” signal dropping out or lagging behind the commanded position. Many times, the fix is a new cam sensor and repairing a brittle connector, but I’ve also seen worn timing chains and damaged camshaft reluctor rings trigger this code.

Symptoms of P0366

• Check engine light on: The MIL will almost always be illuminated when P0366 is stored.
• Rough idle: You may feel shaking or uneven idle speed, especially when the engine is warm.
• Hard starting: Extended cranking or intermittent no-start, particularly when hot.
• Loss of power: Reduced acceleration, sluggish response, or lack of high-RPM power.
• Engine misfires: Random or cylinder-specific misfires, sometimes with additional misfire codes.
• Poor fuel economy: Extra fuel consumption due to incorrect valve timing and ignition timing.
• Stalling: Engine may stall when coming to a stop or at idle, then restart after a short wait.
• VVT performance issues: Variable valve timing may be disabled, causing a “flat” power curve.

Common Causes of P0366

Most Common Causes

• Faulty camshaft position sensor “B” (Bank 1): Internal failure, heat damage, or age-related wear in the sensor itself is one of the top causes.
• Damaged wiring or connector at the cam sensor: Broken wires, loose terminals, corrosion, or oil saturation at the sensor plug can distort the signal.
• Incorrect air gap or mounting issue: If the sensor is not seated fully, has the wrong spacer, or the bracket is bent, the signal can be weak or erratic.
• Timing chain/belt wear or stretch: Excess slack or misalignment changes the camshaft-to-crankshaft relationship and can trigger range/performance codes.
• Dirty or damaged reluctor/trigger wheel: Missing teeth, cracks, or heavy sludge on the camshaft tone ring can cause signal dropouts.

Less Common Causes

• Oil control (VVT) solenoid problems: A sticking or failed VVT solenoid can cause the camshaft to move unpredictably, confusing the ECU.
• Low oil level or poor oil quality: On engines that rely heavily on oil pressure for cam phasing, dirty or low oil can cause erratic cam timing.
• ECU/PCM software issues: Occasionally, a reflash or updated calibration is needed to correct overly sensitive monitoring logic.
• Internal engine damage: Worn camshaft, broken cam phaser, or timing components failing can all cause the cam signal to go out of range.
• Previous incorrect repairs: Wrong sensor part number, aftermarket parts with poor signal quality, or misrouted wiring can all lead to recurring P0366.

Diagnosis: Step-by-Step Guide

To diagnose P0366 properly, you’ll want at least a basic OBD-II scan tool, a digital multimeter (DMM), and ideally access to wiring diagrams and live data. A lab scope is great for viewing the sensor waveform, but many DIYers can still narrow things down with simpler tools and careful inspection.

1. Confirm the code and check for companions: Scan for all stored and pending codes. Note any related cam/crank or VVT codes (like P0340–P0399) that may point to a shared issue.
2. Inspect the camshaft sensor “B” and connector: Locate the Bank 1 cam sensor “B” (often an exhaust cam sensor). Look for cracked housings, oil intrusion, broken locks, or green/white corrosion on terminals.
3. Check the wiring harness: Follow the harness a couple of feet from the sensor. Look for chafing on brackets, melted insulation near the exhaust, or previous repairs using crimp-on connectors or tape blobs.
4. Verify power, ground, and signal reference: With the key on (engine off), use a DMM to check for proper 5V reference (or 12V, depending on design), solid ground, and continuity on the signal wire back to the ECU.
5. Monitor live data for camshaft position: With the engine running, watch the camshaft “B” actual position versus commanded (if your scanner supports it). Look for sudden jumps, dropouts, or values that don’t track with engine speed.
6. Check for mechanical timing issues: If you hear chain rattle, see cam/crank correlation codes, or have high mileage, inspect timing marks. On many engines this requires removing covers to verify the chain or belt alignment.
7. Inspect the reluctor/trigger wheel: Where accessible, visually check the camshaft tone ring for missing teeth, cracks, or heavy sludge buildup that could interfere with the magnetic sensor.
8. Use Mode $06 (if available): Some scan tools allow you to view cam/crank test results in Mode $06. This can show how close the system is to failing before the code sets and help confirm an intermittent issue.
9. Substitute a known-good sensor: If power, ground, and wiring check out, and mechanical timing looks good, swapping in a quality new cam sensor is often the next logical step.
10. Consider ECU testing or reflash: Only after all other possibilities are ruled out should you suspect the ECU. Check for TSBs (technical service bulletins) about software updates related to camshaft sensor codes.

Pro tip: Always use an OEM or high-quality aftermarket cam sensor. Cheap sensors often produce weak or noisy signals and can cause P0366 to come right back after replacement.

Possible Fixes & Repair Costs

Repairs for P0366 range from simple sensor replacement to more involved timing work. A new camshaft position sensor typically runs $40–$150 for the part, with 0.5–1.0 hour of labor at most shops. Wiring repairs can range from $100–$300 depending on how deep the harness damage goes. If the timing chain, belt, or cam phaser is at fault, you’re usually looking at $600–$1,500+ in parts and labor. Costs vary with vehicle make, engine design, labor rates in your area, and whether additional components (guides, tensioners, seals) are replaced at the same time.

Can I Still Drive With P0366?

In many cases, you can still drive with P0366 for a short period, especially if the only symptom is a check engine light and a slightly rough idle. However, if you notice hard starting, stalling, or severe loss of power, you should minimize driving and get it checked quickly. The risk is that what starts as a sensor or wiring issue could actually be the early sign of a timing chain or cam phaser problem, which can worsen and lead to more expensive damage if ignored.

What Happens If You Ignore P0366?

Ignoring P0366 can lead to progressively worse driveability, poor fuel economy, and potential damage to the catalytic converter from misfires. If the underlying cause is a worn timing chain or failing cam phaser, you could eventually face serious internal engine damage. It’s best to diagnose and repair the issue before it escalates.

Last updated: February 13, 2026

Vehicles Commonly Affected by P0366

P0366 shows up across many brands, but it’s especially common on engines that use dual overhead cams and variable valve timing. You’ll frequently see it on GM vehicles (Chevrolet, GMC, Buick, Cadillac V6 and V8 engines), Ford and Lincoln models with DOHC V6/V8 engines, Chrysler, Dodge, and Jeep vehicles with Pentastar and HEMI engines, and various Hyundai, Kia, Nissan, BMW, and Volkswagen/Audi models. It’s also seen on some Subaru and Honda engines. High mileage, poor maintenance, and extended oil change intervals tend to increase the likelihood of this code appearing.