U0090 indicates that the voltage on the Controller Area Network (CAN) Bus G High circuit is higher than specified, typically due to a short to battery voltage or an internal module fault. This code sets when the supervising control module detects that the Bus G High line is stuck at a high voltage level, preventing normal serial communication between networked modules.
The CAN High wiring for Bus G has chafed through or melted against a battery voltage source, or the harness was damaged during service, causing the bus to be pulled permanently high.
A break, severe corrosion, or poor splice in the Bus G High or Low circuits can cause abnormal voltage levels that the PCM interprets as a 'High' fault.
Corroded, bent, or pushed-out pins in the Bus G network connectors allow unintended contact with adjacent power circuits or create signal reflections that bias the line high.
A control module connected to Bus G—such as a body control module, infotainment unit, or telematics module—has an internal driver failure that holds the bus line at battery voltage.
The PCM itself has a rare internal CAN transceiver failure affecting Bus G; this should only be considered after verifying wiring integrity and isolating all other modules.
No. This code almost always stems from wiring shorts, connector issues, or a faulty module on the bus rather than the PCM itself. The PCM should only be suspected after exhaustive testing of the network wiring and all other connected modules.
Driving is possible but not advisable. Communication failures can cause unpredictable behavior in safety systems, instrument clusters, or powertrain controls, potentially leading to sudden loss of function.
Bus G is typically an auxiliary CAN bus used for non-powertrain modules such as infotainment systems, body control modules, telematics, or advanced driver-assistance systems; the exact configuration varies by manufacturer and model year.
Common causes include wiring insulation chafing against a metal frame or power feed, water intrusion into connectors creating conductive paths, or internal semiconductor failure within a connected control module.