What causes fault code P0390?

• Most likely: Faulty Camshaft Position Sensor (internal short or open circuit) • Likely: Damaged wiring harness or corroded connectors • Possible: Damaged or fouled reluctor wheel/tone ring • Rare: Timing belt/chain misalignment or stretched chain affecting synchronization • Very rare: Faulty Engine Control Module (PCM)

Powertrain (Engine & Gearbox)Standard EOBD

P0390 - Camshaft Position Sensor B Circuit (Bank 2)

Q: What are the symptoms of fault code P0390?

• Check Engine Light (MIL) illuminated • Engine may be hard to start (extended cranking) • Rough idling or engine stalling • Loss of engine power or limp mode activation • Decreased fuel economy

Q: How do you fix fault code P0390?

STEP 1: Inspect the connector at sensor B (Bank 2) for corrosion, moisture, or bent pins. Clean with contact cleaner. STEP 2: Use a multimeter to verify reference voltage (typically 5V or 12V) and ground integrity (< 0.1 Ohm to chassis). STEP 3: Test the sensor output. For a 3-wire Hall-effect sensor, use an oscilloscope to check for a clean square wave signal while cranking. STEP 4: Check for mechanical timing issues if the code persists or is accompanied by P0018 (Bank 2 Correlation). STEP 5: Replace the Camshaft Position Sensor if measurements indicate internal failure. Clear codes and perform a drive cycle.

Last updated:1 February 2026

Related:Camshaft Position Sensor, Crankshaft Position Sensor, Wiring Harness, Engine Control Unit (ECU), Camshaft Position Sensor

System

Powertrain (Engine & Gearbox)

Related Fault Codes

P0300

Random or Multiple Cylinder Misfire Detected

P0301

Cylinder 1 Misfire Detected

P0302

Cylinder 2 Misfire Detected

P0303

Cylinder 3 Misfire Detected

Technical Description

P0390 is a standard OBD-II trouble code indicating a malfunction in the Camshaft Position (CMP) sensor 'B' circuit on Bank 2. The PCM (Powertrain Control Module) monitors the voltage signal from the sensor to determine the position and speed of the camshaft. If the PCM detects a lost or erratic signal that does not match the crankshaft position sensor (CKP) pattern, this code is triggered. This disrupts the timing for fuel injection and ignition spark.

Possible Causes

Faulty Camshaft Position Sensor (internal short or open circuit)

Damaged wiring harness or corroded connectors

Damaged or fouled reluctor wheel/tone ring

Timing belt/chain misalignment or stretched chain affecting synchronization

Very rare: Faulty Engine Control Module (PCM)

Symptoms

Check Engine Light (MIL) illuminated

Engine may be hard to start (extended cranking)

Rough idling or engine stalling

Loss of engine power or limp mode activation

Decreased fuel economy

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P0390 - Camshaft Position Sensor B Circuit (Bank 2)

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P0390 - Camshaft Position Sensor B Circuit (Bank 2)

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