Diagnostic trouble code U0248 indicates that the engine control module (ECM) or another control module has lost communication with the remote accessory module (RAM). This module typically manages features like remote keyless entry, power windows, and remote start. The code is set when no messages are received from the RAM over the controller area network (CAN) bus for a specified period.
The RAM itself is the most common failure point due to internal electronic component failure, water damage, or corrosion. This module is often located in the passenger compartment or under the dash.
A blown fuse, corroded connector, or broken wire supplying power or ground to the RAM can prevent it from operating and communicating on the network.
Damage to the twisted-pair CAN bus wires (CAN-H and CAN-L) between the RAM and other modules can disrupt communication. This includes chafed wires, broken wires, or shorts to power/ground.
Corrosion, bent pins, or poor terminal contact at the RAM connector can cause intermittent or complete loss of communication.
A weak battery or failing alternator can cause system voltage to drop below the threshold required for proper module communication.
In rare cases, a failing ECM or another module on the same CAN bus can disrupt communication. However, this is much less common than a problem with the RAM itself.
Yes, in most cases the vehicle will still run and drive, but you may lose convenience features like remote keyless entry, power windows, or remote start. If the vehicle fails to start, it may be due to an immobilizer issue related to the RAM.
No, but it is the most common cause. Always check power, ground, and wiring first. A blown fuse or corroded connector can mimic a failed module. Only replace the module after verifying that it is not receiving proper power/ground or that it fails to communicate on a known-good bus.
Often yes, because the module may need to be configured to the vehicle's options (e.g., keyless entry settings). Some aftermarket modules are plug-and-play, but many require programming with a professional scan tool. Check your vehicle's service information for specific requirements.
Yes, a weak battery or poor charging system can cause voltage drops that disrupt module communication. Always verify battery health and charging voltage before replacing any module. This is a common overlooked cause.