U0036
Vehicle Communication Bus A (-) shorted to Bus A (+)
Communication network (CAN bus)
Generic OBD-II
High
What it means
U0036 means the two wires of communication Bus A — CAN-high and CAN-low — are shorted together, which collapses the bus so modules can no longer talk. This tends to take several modules offline at once and light up multiple systems. Which functions are affected depends on what "Bus A" carries on your specific vehicle.
High
Can I keep driving? Drive with caution — the two bus wires shorted together can collapse the whole bus segment and take multiple modules offline, which may disable safety systems or trigger limp mode.
Common symptoms
What you'll notice
- Multiple warning lights on at once (check-engine, ABS, airbag, and others)
- Many modules on Bus A unreachable with a scan tool
- Features across several systems stop working together
- Possible reduced power or limp mode if a powertrain module is on this bus
Common causes
Most likely first
- CAN-high and CAN-low wires shorted together from crushed, pinched, or melted insulationLikely
- Water or corrosion bridging the two bus wires at a connector or spliceCommon
- A failed module internally shorting the two bus linesCommon
- Damaged harness after a repair, accident, or rodent chewLess often
- Backprobe or repair splice bridging the pairLess often
How to diagnose & fix
Work through it in order
- Scan all modules and note which are unreachable to bracket the shorted section of harness.
- Measure resistance between CAN-high and CAN-low — a near-zero reading confirms the short.
- Inspect Bus A wiring end to end for pinched, melted, or chewed insulation and water intrusion.
- Disconnect modules one at a time; if the short clears when one is unplugged, that module is failed.
- Repair or replace the shorted harness section or module, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with U0036?+
Only briefly if needed — a shorted bus can knock several modules offline, disabling ABS, stability control, or airbags, so get it fixed before regular driving.
Can I just clear U0036?+
No — a wire-to-wire short is a hard fault that returns immediately until the shorted harness or module is repaired.
Related codes
Often seen with U0036
Read & clear U0036 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