U1171: Telematics Module Communication Failure
The U1171 code indicates that the cellular phone control module (or telematics modem) is not transmitting valid data or has stopped communicating on the SCP (Standard Corporate Protocol) J1850 bus. This low-speed bus handles communication between body and accessory modules. The absence of periodic heartbeat messages or corrupted data from the phone module causes the PCM or another master module to log this network DTC.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty or internally damaged cellular phone/telematics module
- Open circuit, short to ground/battery, or high resistance in the SCP bus (+/-) wiring to the phone module
- Loose, corroded, or retracted terminals in the phone module connector
- Loss of power (B+) or ground to the phone module
- SCP bus collapsed due to another module monopolizing communication
- Incorrect programming or software incompatibility after module replacement
3. Symptoms You Will Notice
- Check Engine Light or other warning lights illuminated
- Inoperative telematics features (e.g., Bluetooth, emergency call, navigation)
- Possible communication issues with other body modules
4. Step-by-Step Diagnosis
Scan for all DTCs and note any related network codes
Inspect the phone module connector for corrosion, damage, or loose pins
Check power and ground at the phone module (B+ and ground circuits)
Test SCP bus wiring for opens, shorts, or high resistance between the module and the bus
If wiring is OK, suspect the phone module itself; try reprogramming or replacement
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, the vehicle is generally safe to drive, but telematics features like Bluetooth or emergency calling may not work. Have it diagnosed soon to avoid potential battery drain or other issues.
How much does it cost to fix?▼
Diagnosis typically costs $100-$150. If the module needs replacement, parts and labor can range from $300 to $800, depending on the vehicle and module type.