P047C
Exhaust Pressure Sensor B Circuit Low
Exhaust pressure / emissions
Generic OBD-II
Medium
What it means
P047C means the second exhaust pressure (back-pressure) sensor circuit is reading low. Like sensor A, this sensor helps the computer manage EGR and the particulate filter on diesels and some turbo engines. A low or lost signal can trigger reduced-power or limp mode to protect the engine, but the car still runs and starts.
Medium
Can I keep driving? Often reduced — the engine may enter limp mode with lower power; drive gently to get it diagnosed, but avoid towing or hard acceleration.
Common symptoms
What you'll notice
- Check-engine light on
- Reduced power or acceleration
- Engine may enter limp mode
- Decreased fuel efficiency
Common causes
Most likely first
- Faulty exhaust back-pressure sensor (sensor B)Likely
- Wiring shorted low or open in the sensor circuitCommon
- Corroded or loose sensor connectorCommon
- Clogged or damaged pressure sense tube to the sensorLess often
- ECM fault (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame data and inspect the sensor B connector and wiring for shorts, opens, and corrosion.
- Check the sensor's pressure tube/port for soot clogging or damage and clean or replace as needed.
- Compare the sensor signal to spec; replace the sensor if it reads low or out of range.
- If wiring and sensor check out, have the ECM evaluated. Clear the code and re-test.
FAQ
Quick answers
Is it safe to drive with P047C?+
Only gently. The engine may enter limp mode and lose power. Get it diagnosed soon and avoid towing or hard driving until it's fixed.
Can I just clear P047C?+
No lasting fix — it returns once the low signal is seen again. The sensor, wiring, or sense tube for exhaust pressure sensor B needs repair.
Related codes
Often seen with P047C
Read & clear P047C yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX