U0077Network Communication
Control Module Communication Bus E Off
U0077 means a module detected communication bus E has shut down (bus off). Bus E is a separate network with its own group of modules.
🚗 Not recommended. A bus-off condition can disable systems and cause erratic behavior.
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🎯 Top Causes, Ranked by Likelihood
#1Short on bus E wiring$50-$500
A short to power or ground forces bus E off; inspect that harness.
#2Failed module on bus E$200-$1000
A faulty module can corrupt bus E; isolate by disconnecting modules.
#3Poor grounds or power$50-$300
Weak grounds cause communication faults.
#4Connector or terminal damage$50-$300
Corroded or bent pins interrupt bus signals.
🩺 Common Symptoms
- Multiple warning lights
- Bus E modules offline
- Erratic accessory operation
- Possible drivability faults
💰 Repair Cost: DIY vs Shop
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🔧 How to Diagnose U0077
1Identify bus E modules in the wiring diagram
2Check bus E resistance and voltage
3Inspect bus E wiring for shorts and damage
4Disconnect bus E modules one at a time to isolate the fault
❓ Frequently Asked Questions
Can I drive with U0077?
It is not recommended. Losing a bus can disable systems and cause erratic behavior. Diagnose it first.
What causes U0077?
A short or wiring fault on bus E, or a single failed module dragging that bus offline.
How is U0077 diagnosed?
Identify which modules use bus E, then test the wiring and isolate modules methodically.
🔗 Related Codes
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