P0396 – Ignition Coil “O” Primary/Secondary Circuit

P0396 is an OBD-II trouble code that points to an electrical problem with the camshaft position sensor “B” on Bank 2, specifically an intermittent or erratic signal. In plain terms, your engine computer is seeing a cam signal that cuts in and out or doesn’t stay within the expected range. This can cause rough running, hard starts, and sometimes stalling. While it’s not usually an immediate engine killer, you shouldn’t ignore it. Left unfixed, it can lead to drivability issues, poor fuel economy, and potential damage to other components.

What Does P0396 Mean?

P0396 stands for “Camshaft Position Sensor ‘B’ Circuit Intermittent (Bank 2).” Bank 2 is the side of the engine that does not contain cylinder #1, and sensor “B” usually refers to the exhaust camshaft sensor on that bank (though some manufacturers may label it slightly differently).

The engine control unit (ECU) relies on the camshaft sensor signal to time fuel injection and ignition events. When the signal from sensor “B” on bank 2 drops out, becomes noisy, or shows up inconsistently, the ECU flags P0396. The issue can be inside the sensor itself, the wiring, or less commonly the ECU.

Quick Reference

• Code: P0396
• Definition: Camshaft Position Sensor “B” Circuit Intermittent (Bank 2)
• Severity: Moderate – can affect drivability and starting
• Most common cause: Failing camshaft position sensor or damaged wiring
• Typical fix: Sensor replacement and wiring repair as needed

Real-World Example / Field Notes

In the shop, P0396 often walks in as a car that “sometimes cranks a long time before starting” or “runs fine, then suddenly stumbles and the check engine light comes on.” On a V6 SUV I worked on, the owner had already replaced spark plugs and coils chasing a misfire. Scan data showed the camshaft signal on bank 2 exhaust dropping out randomly while the engine was warm. Wiggling the harness at the sensor made the signal glitch on the scope. A new connector pigtail and sensor fixed the issue permanently.

Symptoms of P0396

• Check engine light illuminated, sometimes with no obvious drivability change at first.
• Hard starting, especially when the engine is hot or after a short shutdown.
• Rough idle or intermittent stumbling, as the ECU struggles to track cam position.
• Loss of power or sluggish acceleration under load or at certain RPM ranges.
• Engine hesitation or brief cut-outs while cruising.
• Poor fuel economy due to incorrect timing and enrichment strategies.
• Occasional stalling, particularly when coming to a stop or during hot restarts.

Common Causes of P0396

Most Common Causes

• Failing camshaft position sensor “B” (Bank 2): Internal electronics break down, causing intermittent voltage or signal dropout, often worse when hot.
• Damaged wiring harness to the sensor: Chafed, melted, or oil-soaked wires causing intermittent shorts or open circuits.
• Loose or corroded connector at the cam sensor: Poor pin contact can create an erratic signal, especially with vibration.
• Oil contamination inside the sensor (on some designs): Oil intrusion can disrupt the Hall-effect sensor or magnetic pickup.

Less Common Causes

• Timing chain or belt issues: Excessive slack, a stretched chain, or a jumped tooth can cause erratic cam timing that the ECU interprets as an intermittent signal.
• Damaged camshaft reluctor ring (trigger wheel): Bent, cracked, or missing teeth can cause irregular pulses.
• Poor engine ground or power supply to the sensor or ECU: Voltage drops can corrupt the signal.
• ECU internal fault: Rare, but possible if all other causes have been ruled out.
• Aftermarket remote start or wiring mods: Poorly spliced wiring near the engine harness can introduce intermittent faults.

Diagnosis: Step-by-Step Guide

Basic tools you’ll want include an OBD-II scan tool (preferably one that shows live data and Mode $06), a digital multimeter, and if possible an oscilloscope for viewing sensor waveforms. A wiring diagram for your specific vehicle is also very helpful.

1. Confirm the code and check for companions. Scan for all stored and pending codes. Note any related camshaft, crankshaft, or timing codes (like P0017 or P0390). Clear the codes and see if P0396 returns quickly.
2. Check live data. Look at camshaft position data for Bank 1 vs Bank 2, and sensor A vs B. If your scan tool supports it, watch the camshaft correlation and see if Bank 2 exhaust (sensor B) drops out or freezes while running.
3. Visual inspection. Locate the Bank 2 sensor “B” (usually exhaust side on the bank opposite cylinder #1). Inspect the connector, wiring, and routing. Look for oil saturation, broken conduit, sharp bends, or contact with hot exhaust components.
4. Wiggle test. With the engine idling and scan data or a scope connected, gently move the harness and connector. If the engine stumbles or the signal glitches when you move a certain spot, you’ve likely found a wiring or connector issue.
5. Check sensor power and ground. Using a multimeter, verify that the sensor has proper reference voltage (usually 5V), ground, and signal return according to the wiring diagram. A missing 5V or weak ground can cause intermittent operation.
6. Measure sensor resistance (if applicable). Some sensors have specified resistance values. Remove the connector and compare your readings to service manual specs. Out-of-range or unstable readings indicate a bad sensor.
7. Scope the signal (best method). If you have an oscilloscope, monitor the camshaft sensor signal while the engine is idling and being lightly revved. You’re looking for a clean, consistent square wave or sine wave (depending on design), not one that drops out or becomes noisy.
8. Inspect mechanical timing. If electrical checks pass but the code persists, inspect timing chain/belt condition and camshaft reluctor ring. Excessive slack or damage can cause irregular cam signals.
9. Use Mode $06 data. On some vehicles, Mode $06 will show cam/crank correlation test results. This can confirm an intermittent failure even if the code isn’t currently active.
10. Substitute a known-good sensor. As a final step, if everything points to the sensor but tests are inconclusive, installing a quality replacement can confirm the diagnosis.

Pro tip: Always use an OEM or high-quality aftermarket camshaft sensor. Cheap sensors often cause more intermittent issues than the original part you’re trying to fix.

Possible Fixes & Repair Costs

Most repairs for P0396 are straightforward once you pinpoint the cause. The most common fix is replacing the Bank 2 camshaft position sensor “B” and addressing any wiring issues. Typical repair costs vary based on vehicle design, parts quality, and shop labor rates, but you can use these ranges as a guide.

• Replace camshaft position sensor “B” (Bank 2): $80–$250 total. Parts usually run $40–$120, with 0.5–1.0 hour labor in most vehicles.
• Repair or replace wiring/connector: $100–$300, depending on how much harness needs to be repaired and accessibility.
• Timing chain/belt repair (if stretched or jumped): $600–$1,800+, depending on engine design and whether other components (tensioners, guides, water pump) are replaced.
• ECU repair or replacement: $500–$1,500+, but this is rare and usually a last resort after all other causes are ruled out.

Costs are affected by where the sensor is located (easy access vs buried under intake manifolds), local labor rates, whether you use OEM parts, and whether additional issues (oil leaks, broken connectors) are found during the repair.

Can I Still Drive With P0396?

In many cases you can still drive with P0396 for a short period, but it’s not ideal. If the sensor signal only cuts out occasionally, you might just notice a check engine light and minor performance issues. However, if the signal becomes more erratic, you can experience hard starts, stalling, or loss of power at the worst possible time. If the engine runs very rough, stalls, or struggles to start, you should avoid driving and have it diagnosed as soon as possible.

What Happens If You Ignore P0396?

Ignoring P0396 can turn a relatively simple repair into a bigger headache. Continued driving with an intermittent cam signal can cause long-term timing issues, poor fuel economy, and extra stress on the catalytic converters from unburned fuel. You also risk sudden stalling or no-start situations, which can leave you stranded. Addressing the sensor or wiring problem early usually keeps the repair inexpensive and straightforward.

Last updated: March 1, 2026

Vehicles Commonly Affected by P0396

P0396 shows up most often on V6 and V8 engines that use multiple camshaft sensors per bank. You’ll commonly see it on late-model GM vehicles (Chevrolet, GMC, Cadillac, Buick) with 3.6L and 5.3L engines, as well as some Ford V6/V8 applications. It’s also seen on certain Nissan and Infiniti VQ-series V6 engines, and some Hyundai and Kia V6 models. Any dual overhead cam (DOHC) engine with separate intake and exhaust cam sensors on each bank can potentially set P0396 when the Bank 2 exhaust cam sensor or wiring acts up.