OBD-II Code P0393 — What It Means & How to Fix It

What Does This Error Mean?

P0393 means the PCM is reading a signal voltage on the camshaft position sensor B circuit on Bank 2 that is higher than the maximum acceptable level. Sensor B is the exhaust camshaft sensor. Bank 2 is the engine side without cylinder number 1. High signal voltage usually indicates a short to power (voltage) in the wiring, or a failed sensor stuck at the supply voltage.

Affected Models

All 1996+ V6, V8, and V10 vehicles with DOHC engines and exhaust cam position 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 GM DOHC V6 and V8 vehicles
Common in Hyundai and Kia DOHC engines with CVVT variable valve timing

Common Causes

Camshaft position sensor B on Bank 2 with an internal short to the 5V reference supply
Short circuit to voltage in the sensor signal wire — the wire is contacting a power supply wire
Corroded connector bridging the signal pin to the reference voltage pin
Damaged wiring harness where the signal wire contacts a nearby power wire
PCM reference voltage output stuck high on the Bank 2 cam B input channel (uncommon)

How to Fix It

Disconnect the Bank 2 cam sensor B connector. With the ignition on, measure the voltage on the signal wire pin in the harness connector. It should read near 0V or a low standby voltage with the sensor disconnected. A reading near 5V or higher with the sensor unplugged confirms a short to power in the wiring.

Disconnecting the sensor first is critical. If you measure with the sensor connected and get a high reading, you cannot tell whether it is the wiring or the sensor causing the problem.
Trace the signal wire from the Bank 2 cam sensor B back toward the PCM. Look for areas where the signal wire is bundled tightly with the 5V reference wire or with any other power supply wire. A break in insulation where these two wires touch will cause a persistent high-voltage fault.

Use a wiring diagram to identify which wire in the harness is the signal wire. Signal wires and reference voltage wires are often similar in color, so relying on wire color alone is unreliable. Use the diagram.
Inspect the sensor connector closely for bridged or touching pins. Corrosion or a bent pin that contacts the adjacent reference voltage pin can apply 5V to the signal wire without any wiring damage. Use a connector pick to straighten bent pins and clean with electrical contact cleaner.

Even a thin film of conductive corrosion bridging two pins can cause a high-input code. A thorough cleaning of the connector often resolves this without any part replacement.
Replace the cam sensor B on Bank 2 if the wiring and connector are clean. A sensor with an internal short to the reference voltage rail will produce a constant high output. Install the correct sensor for your vehicle and bank, then reconnect firmly.

Buy the part using your vehicle VIN to ensure the correct sensor for Bank 2, exhaust camshaft. An incorrect sensor may fit physically but produce incorrect output voltage.
Clear all DTCs and test drive the vehicle. If P0393 returns on a new sensor with verified clean wiring, schedule a professional diagnosis to check the PCM signal input channel. Do not keep replacing parts without confirming the PCM is not the issue.

Repeated high-input codes on a new sensor with no wiring fault is one of the clearest indicators of a PCM-level problem. A lab scope at the PCM connector will confirm or rule this out in minutes.

When to Call a Professional

If the wiring is clean and the sensor is new but P0393 persists, the PCM input channel may be internally stuck at high voltage. A technician can confirm this by measuring the signal voltage at the PCM connector with the sensor and all wiring disconnected. Diagnosis typically runs $80-$150. PCM repair or replacement is expensive — $300-$900 or more depending on the vehicle.

Frequently Asked Questions

What causes a signal wire to short to power?

The insulation on the wire has been damaged — usually by heat, abrasion, or pinching. When the insulation breaks down, the bare wire inside can contact a nearby power wire. This is most common where the harness is routed near hot engine components, clamped tightly against a bracket, or passes through a grommet that has deteriorated. Previous repair work that pinched a wire under a fastener can also cause this.

Is P0393 the same as P0368 but on Bank 2?

Yes, exactly. P0368 is a high-input fault for the Bank 1 exhaust cam sensor. P0393 is the same fault type for Bank 2. The causes, diagnostic approach, and repair steps are identical — only the physical location on the engine is different.

Can P0393 damage the PCM?

In extreme cases, a sustained short to a high voltage on an input pin can damage the PCM input circuit. This is more likely if battery voltage is being applied to the signal pin rather than just the 5V reference. For most cases involving a short to the 5V reference, the PCM input is protected and will survive. However, fixing the short quickly is still important to prevent any long-term degradation.