Vehicle Communication Bus E (-) Low
What it means
U0070 means the voltage on the negative wire of vehicle communication bus E is lower than expected — typically a short to ground or a bad connection on the data network. Modules on bus E can't communicate reliably, so features fail and warning lights appear. The severity depends on which systems use bus E: a body network just loses features, while a powertrain network can cause stalling or a no-start. It is normally a wiring or connector problem.
Can I keep driving? Depends on the network — a low signal on bus E can mean anything from a few dead features to a no-start if it carries the powertrain, so diagnose before relying on the car.
Common symptoms
What you'll notice
- Multiple warning lights on at once
- Modules on bus E missing or responding intermittently
- Features tied to bus E stop working
- Possible stalling or no-start if bus E serves the engine or transmission
Common causes
Most likely first
- Bus E negative circuit shorted to ground, pulling the voltage lowLikely
- Chafed wiring touching chassis groundCommon
- Corroded or water-damaged connector dragging the signal downCommon
- A failing module loading the busLess often
- Damaged splice or terminal from a prior repairLess often
How to diagnose & fix
Work through it in order
- Check which modules on bus E have dropped off to narrow the affected segment.
- Inspect the bus E negative wiring for chafing or a short to ground where the harness crosses metal edges.
- Measure the (-) circuit voltage and resistance to ground against spec to find the low point.
- Disconnect suspect modules one at a time to see if the bus voltage recovers.
- Repair the shorted wiring or replace the faulty module, then clear and re-test.
FAQ
Quick answers
Is it safe to drive with U0070?+
Can I just clear U0070?+
Related codes
Often seen with U0070
Read & clear U0070 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.