The ECM detects a circuit high fault on the turbocharger/supercharger b temperature sensor. Reading cannot be used reliably for control.
Medium severity. Can I keep driving?Drive without demanding power and go to a repair shop soon. If you see a lot of blue smoke or hear a metallic noise, shut off the engine.
Symptoms
- Check engine light on
- Significant power loss / limp mode
- Possible blue or black smoke from exhaust
- Whistling or hissing sound from intake
Most likely causes
- Signal wire shorted to B+
- Open sensor
- Connector pins corroded - high contact resistance
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: easy
- It affects emissions.
What each character of P2B91 means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- B: Subsystem depends on the code range
- 91: Specific fault in that system
Frequently asked questions
Can I keep driving with code P2B91?
Drive without demanding power and go to a repair shop soon. If you see a lot of blue smoke or hear a metallic noise, shut off the engine.
What causes code P2B91?
The most common causes are: signal wire shorted to B+; open sensor; connector pins corroded - high contact resistance.
Related codes
Sources
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.