OBD-II Code P0390 — What It Means & How to Fix It

What Does This Error Mean?

P0390 means the PCM detected an electrical fault in the camshaft position sensor B circuit on Bank 2. Sensor B refers to the exhaust camshaft in DOHC engines. Bank 2 is the side of the engine that does NOT contain cylinder number 1. Expect rough idle, possible misfires on the Bank 2 side, and reduced fuel economy.

Affected Models

All 1996+ V6, V8, and V10 vehicles with DOHC engines and separate exhaust cam sensors
Common in Toyota and Lexus V6 and V8 vehicles with VVT-i
Common in Honda and Acura V6 engines with i-VTEC
Common in Ford V6 and V8 engines with Ti-VCT dual VCT
Common in GM V6 and V8 DOHC engines with variable valve timing

Common Causes

Failed camshaft position sensor B on Bank 2
Damaged, corroded, or broken wiring in the Bank 2 cam sensor B circuit
Loose or corroded harness connector at the Bank 2 cam sensor B plug
Metal shavings or debris on the camshaft reluctor ring affecting the sensor signal
Stretched timing chain on Bank 2 causing cam position to deviate from expected values

How to Fix It

Confirm which side of your engine is Bank 2. Bank 2 is always the side that does NOT contain cylinder number 1. On most domestic V8s, cylinder 1 is at the front of the driver's side bank, making the passenger side Bank 2. This varies by manufacturer — always verify.

Getting the bank wrong is a common and costly mistake. Look up a cylinder numbering diagram for your exact engine before pulling any sensor.
Inspect the camshaft position sensor B connector on Bank 2. Look for corrosion, damaged wires, pushed-back terminals, or a connector that is not fully locked. Clean the connector with electrical contact cleaner and reseat it firmly.

On V6 engines the Bank 2 sensors are often tucked against the firewall where they are harder to access and more prone to connector issues from heat and vibration.
Check engine oil level and condition. Low or degraded oil affects the VVT system on Bank 2 just as much as Bank 1. Change the oil if it is overdue. Good oil pressure is essential for the cam timing system to function properly.

Many cam sensor codes on VVT-equipped vehicles trace back to oil-related issues. Check and change the oil before spending money on sensors or wiring repairs.
Replace the camshaft position sensor B on Bank 2 if wiring checks are clean. Use the correct part for your engine — confirm it is for Bank 2, exhaust camshaft. Reconnect the harness firmly and clear all DTCs.

On DOHC engines, the intake and exhaust cam sensors can look identical but may have different calibrations. Always buy the part using your VIN to confirm the exact application.
Clear all codes and drive through a full warm-up cycle. Recheck with a scanner. If P0390 returns, use live scan data to compare actual Bank 2 cam B position to commanded position. A large and consistent offset indicates a timing chain or VVT actuator problem.

A timing chain that has stretched will cause the Bank 2 cam B position to read consistently retarded compared to what the PCM commanded. This requires mechanical repair, not just sensor replacement.

When to Call a Professional

If sensor replacement and wiring inspection do not resolve P0390, the problem may be a mechanical timing issue on the Bank 2 side. A stretched timing chain or sticking VVT actuator on Bank 2 can also cause this code. Timingchain diagnosis and repair is a professional-level job on most V6 and V8 engines. Diagnosis runs $80-$150 at most shops. Timing chain repairs can cost $700-$2,500 depending on the engine.

Frequently Asked Questions

How do I find Bank 2 on my engine?

Bank 2 is the side of the engine that does not contain cylinder number 1. On most American V8 engines, cylinder 1 is front-left (driver side), making Bank 2 the passenger side. On many Japanese V6 engines, the front bank facing the radiator is often Bank 1, making the rear bank Bank 2. Your vehicle's service manual will have a cylinder layout diagram — always check it before assuming.

Is P0390 the same as P0365 but for the other bank?

Essentially yes. P0365 is a camshaft position sensor B circuit fault on Bank 1. P0390 is the same fault type, but on Bank 2. The causes, diagnosis steps, and repairs are identical — the only difference is which physical sensor and which side of the engine is involved.

Can P0390 cause my car to run rough only on one side?

Yes. A fault with the Bank 2 exhaust cam sensor can disrupt variable valve timing on that bank. This can cause the Bank 2 cylinders to run with incorrect valve timing, producing an asymmetric rough idle. On a V6, this may feel like a 3-cylinder misfire on one side. On a V8 it can feel similar but is sometimes harder to notice until you check live data on a scanner.