With P2B49 the module reads too low a signal from position sensor B at the exhaust camshaft actuator of bank 1. A short between signal line and ground, a sensor with an internal short or a missing feed are the usual suspects. The nearest public manufacturer reference is P34BE on the Mercedes M176/M177: the sensor of exhaust solenoid 1 for CAMTRONIC, bank 1, described as shorted to ground. For P2B49 itself no manufacturer document is available. GM sets the comparable exhaust code of its L3B (P2C14) when the driver is on and the circuit shows at most 0.5 Ω to ground. Chafe points on the harness running along the cylinder head cover are worth checking first. Exhaust bank 1 high fault: P2B4A.
Medium severity. Can I keep driving?Drive little and gently. If you hear timing chain noise or the oil light comes on, shut off the engine.
Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank.
Symptoms
- Check engine light on
- Exhaust cam lift change switched off
- Occasionally further sensor codes
Most likely causes
- Signal line shorted to ground
- Sensor shorted internally
- Sensor feed missing
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: medium
- It can trigger limp mode.
- It affects emissions.
What each character of P2B49 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- B: Subsystem depends on the code range
- 49: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2B49?
Drive little and gently. If you hear timing chain noise or the oil light comes on, shut off the engine.
What causes code P2B49?
The most common causes are: signal line shorted to ground; sensor shorted internally; sensor feed missing.
Related codes
- P2B41A Camshaft Position Actuator Position Sensor B Circuit Low Bank 1
- P2B47B Camshaft Position Actuator Position Sensor B Circuit Bank 1
- P2B48B Camshaft Position Actuator Position Sensor B Range/Performance Bank 1
- P2B4AB Camshaft Position Actuator Position Sensor B Circuit High Bank 1
- P2B4DB Camshaft Position Actuator Position Sensor B Circuit Low Bank 2
- P34BEB Camshaft Position Actuator Position Sensor A Circuit Low Bank 1
- P03F8B Camshaft Position Actuator Position Sensor C Circuit Low Bank 1
Sources
- law.cornell.edu: 13 CCR 1968.2
- ntn-snr.com: TECHinfo CMP UK
- static.nhtsa.gov: MC 11027678 0001
- gsi.ext.gm.com: 19OBDG03D Diagnostics
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.