SCP (J1850) Invalid or Missing Data for Tuner / Receiver
Your vehicle's main computer isn't receiving proper data from the radio tuner or aftermarket receiver module over the J1850 communication bus. Think of it like a walkie-talkie where one device isn't transmitting clearly, so the main unit can't hear it.
The ECU monitors the J1850 SCP (Standard Corporate Protocol) bus for valid data frames from the tuner/receiver module at regular intervals. It expects to receive periodic heartbeat messages and configuration data; if these messages are absent, corrupted, or timeout, the fault triggers. The ECU validates message checksums and timing windows to detect communication failures.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| J1850 Message Response Time | 50–200 ms between frames | No response or >500 ms delay |
| Data Checksum Validity | CRC or checksum passes | Checksum mismatch or missing data bytes |
Code U1165 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, U1165 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.