OBD-II Code P0394 — What It Means & How to Fix It

What Does This Error Mean?

P0394 means the PCM is occasionally losing or receiving an erratic signal from camshaft position sensor B on Bank 2. Sensor B is the exhaust cam sensor. Bank 2 is the side of the engine without cylinder number 1. Intermittent faults are harder to diagnose because the problem comes and goes — but they still cause the check engine light to stay on once the PCM has counted enough occurrences.

Affected Models

All 1996+ V6, V8, and V10 vehicles with DOHC engines and exhaust cam sensors
Common in aging Toyota and Lexus V6 vehicles with VVT-i at high mileage
Common in Honda and Acura V6 engines as they accumulate miles
Common in Ford DOHC V6 and V8 engines
Common in any vehicle where the Bank 2 cam sensor is in a high-heat or high-vibration location

Common Causes

Failing camshaft position sensor B on Bank 2 with an internal break that fails intermittently under heat or vibration
Loose or intermittently unseated harness connector at the Bank 2 cam sensor B
Wire broken inside the insulation in the harness — opens up under flexing or thermal expansion
Oil contamination slowly degrading sensor signal quality over many months
Slight reluctor ring contamination causing occasional signal dropouts at specific engine speeds

How to Fix It

With the engine running, use one hand to gently wiggle the Bank 2 cam sensor B connector and the harness near the sensor. Watch for any change in idle quality, misfires, or changes in scanner data. An intermittent connection will cause a momentary stumble.

Work slowly and move the harness in different directions. The intermittent break may only open up when the harness is flexed in one specific direction. Take your time and be thorough.
Inspect the Bank 2 cam sensor B for oil contamination. On V-configuration engines, the Bank 2 valve cover is often the rear bank. Valve cover gasket leaks on this bank can drip oil directly onto the sensor and connector over time.

If oil is present at the sensor, replace the valve cover gasket before replacing the sensor. A new sensor installed in an oily environment will develop the same contamination problem again.
Trace the Bank 2 cam sensor B harness looking for sharp bends, areas where the harness is clamped tightly, or spots where it passes through grommets. An internal wire break — a wire broken inside intact insulation — is found by flexing the harness at each suspicious spot while watching for a signal change.

This type of break is called a chafed or fatigued wire. It looks fine from the outside but the copper strands inside have broken from repeated flexing over the years. It only opens up when the harness flexes in a specific way.
Replace the Bank 2 camshaft position sensor B. Even if the sensor looks fine, internal intermittent failures are invisible. The sensor is inexpensive relative to diagnostic labor and replacement eliminates it as a variable.

When installing the replacement, make sure the connector clicks fully into place. A partially locked connector is a common cause of intermittent faults that get misdiagnosed as sensor failures.
Drive the vehicle for 200-300 miles over varied conditions — cold starts, highway, city — to confirm the fault does not return. Intermittent codes need extended observation to confirm resolution. Check the scanner after this extended test period.

If P0394 returns after sensor replacement and connector inspection, bring it to a professional with a lab scope. The intermittent wiring fault needs to be pinpointed before spending more money on parts.

When to Call a Professional

If simple connector and sensor replacement do not stop P0394 from returning, a lab scope is needed to watch the Bank 2 cam B signal continuously. A technician can flex the harness while monitoring the signal in real time — the intermittent break will show up as a brief dropout on the scope trace. Diagnosis for intermittent faults runs $100-$200 due to the additional time required.

Frequently Asked Questions

Why does the check engine light stay on if the problem is only intermittent?

The PCM counts how many times the fault occurs across drive cycles. Once the count crosses a threshold — usually after the fault occurs multiple times within a set number of warm-up cycles — the PCM stores the code and illuminates the check engine light. Even if the fault is brief, it gets counted each time it happens. The light stays on until the code is cleared and the fault does not recur over several drive cycles.

How do I know if my intermittent P0394 is getting worse?

A worsening intermittent fault typically becomes more frequent over time. Watch for the check engine light to come back sooner after clearing the code, or for noticeable drivability symptoms — rough idle, brief stumbles — to appear more often. An intermittent fault that shows up daily is much closer to becoming a continuous fault. Get it fixed before it leaves you stranded.

Is P0394 the same as P0369 but for Bank 2?

Yes. P0369 is an intermittent camshaft position sensor B fault on Bank 1. P0394 is the same type of fault but on Bank 2. The causes and repair steps are identical — only the physical location on the engine is different. If you have both P0369 and P0394 at the same time, suspect a common cause like a wiring harness problem rather than two separate sensor failures.