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DTC codes / P2Bxx · Hybrid propulsion / P2B37

P2B37A Camshaft Profile Actuator B Control Circuit Low Bank 2

P2B37 indicates that the powertrain control module (PCM) has detected a low-voltage condition on the control circuit for the bank 2 camshaft profile actuator, which is the solenoid or motor that changes valve lift or timing profile. The PCM commands the actuator to a specific position and monitors the circuit; when the feedback voltage stays below the expected threshold for a calibrated time, it sets this code and may disable the profile-shifting function.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaHybrid propulsion

Symptoms you may notice

  • Illumination of the check engine light, often with no other noticeable symptoms
  • Reduced engine power or a limp-home mode, especially under heavy load or at higher RPM
  • Rough idle or poor drivability when the cam profile fails to change as commanded
  • Decreased fuel economy because the engine cannot switch to the optimal cam profile
  • In some vehicles, a message on the driver information center indicating a service engine soon or reduced power condition

Common causes, most likely first

  1. Damaged, chafed, or corroded wiring in the bank 2 camshaft profile actuator control circuit
  2. Failed camshaft profile actuator solenoid or motor (open or shorted internal coil)
  3. Poor electrical connection at the actuator or PCM connector, including loose pins or water intrusion
  4. PCM internal driver fault on the low-side control circuit, though this is less common
  5. Low system voltage or a weak battery that causes the actuator circuit to read low during cranking or high load
  6. Aftermarket electrical accessories or poor grounds that introduce voltage drops on the shared circuit

How to diagnose and fix it

  1. Verify battery voltage and charging system output, as low system voltage can mimic a circuit fault
  2. Inspect the actuator connector and wiring harness for damage, corrosion, or loose pins, and repair as needed
  3. Measure resistance across the actuator solenoid and compare to the manufacturer's specification to rule out an open coil
  4. Back-probe the control circuit at the actuator and at the PCM to check for voltage drops or a short to ground with the key on and engine off
  5. Command the actuator with a scan tool and observe circuit voltage or current feedback to confirm whether the PCM driver or the actuator is at fault
  6. If the circuit and actuator test good, substitute a known-good actuator or perform a wiggle test on the harness while monitoring the code to isolate an intermittent fault
  7. Clear the code and perform a road test with the scan tool recording to confirm the repair and ensure the monitor runs to completion

What the low circuit code really means

  • A low circuit code does not automatically mean the actuator is defective; a voltage drop on the ground side or a weak battery can set the same code because the PCM sees less than expected voltage on the control circuit.
  • Many technicians replace the camshaft profile actuator only to find the connector pins have been pushed back or corroded, so always perform a pin drag test and inspect the terminals before condemning the part.
  • On some engines, the bank 2 actuator shares a power or ground circuit with other solenoids, so a fault in a neighbouring component can pull the voltage low and set P2B37 without any problem in the actuator itself.
  • The PCM may set this code only after the engine reaches operating temperature and the profile change is commanded, so a cold-engine test drive can miss an intermittent fault that appears only during a specific driving condition.
  • Aftermarket remote starters or alarm systems that tap into the harness near the PCM can introduce resistance or noise on the control circuit, causing a low-voltage code that disappears when the accessory is disconnected.

Can I keep driving with P2B37?

You can usually drive the vehicle to a repair shop, but avoid heavy acceleration and sustained high RPM because the engine may enter a reduced-power mode when the cam profile cannot change. If the check engine light flashes or the engine runs very poorly, stop driving and have the vehicle towed to prevent damage.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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