OBD-II code · Network
U01B1 Lost Communication With Particulate Matter Sensor B
ECU lost communication with particulate matter sensor B (downstream of DPF, used for DPF integrity monitoring). A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.
Is it safe to drive with U01B1?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelySensor unpowered or wiring broken
- Less likelyGateway module routing CAN messages incorrectly
- Less likelyCAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Often, with basic tools
- Typical labour
- 0.5–3 h
- Emissions test
- Likely to fail
- After the fix
- A drive cycle is needed before the light stays off
- Parts involved
- Pm Sensor B, Can Bus
Related codes
- U01AELost Communication With Hybrid/EV Battery Interface Control Module O
- U01AFLost Communication With Hybrid/EV Battery Interface Control Module P
- U01B0Lost Communication With Battery Monitor Module
- U01B2Lost Communication With Planetary Gear Set Control Module
- U01B3Lost Communication With Brake Blending Actuator
- U01B4Lost Communication With Brake System Control Module B
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.