U0070: CAN Bus E Low Line Fault
The U0070 code indicates a communication failure on the vehicle's E bus, specifically on the Low signal line. According to SAE J2012, codes U0070-U007F correspond to Communication Bus E issues, with U0070 diagnosing the Low line. This bus is a CAN (Controller Area Network) or similar network that enables data transmission between electronic modules. The Low line has abnormal resistance, a short to ground, a short to the High line, or an open circuit that prevents proper communication between modules on this bus.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Terminal resistance on CAN E bus out of spec (not 120 ohms per node)
- Short to ground on the E bus Low line
- Short between Low and High lines on the E bus
- Open or damaged wiring on the E bus Low line
- Corroded, oxidized, or loose connector or module pin
- Internal module failure affecting bus impedance
- Electromagnetic interference from unshielded or damaged wiring
3. Symptoms You Will Notice
- Check Engine Light or other warning lights on
- Multiple modules not communicating, causing drivability issues
4. Step-by-Step Diagnosis
Scan for all codes and note modules that are not communicating
Check CAN E bus resistance at the OBD2 port or module connectors (should be ~60 ohms with two 120-ohm terminators)
Inspect wiring and connectors for damage, corrosion, or loose pins
Isolate the fault by disconnecting modules one at a time while monitoring resistance
5. Frequently Asked Questions
Is it safe to drive?▼
No, driving with U0070 is not recommended as it can cause unpredictable behavior, loss of critical functions, and potential safety hazards.
How much does it cost to fix?▼
Repair costs typically range from $100 to $600, depending on whether it's a simple wiring repair or a module replacement.