U0227: Lost CAN Comm with Window Motor F
The U0227 code indicates that the main control module (typically the Body Control Module or the relevant door module) has lost Controller Area Network (CAN) communication with the power window motor identified as 'F'. This identifier usually corresponds to a specific window motor, often the right rear door, though it may vary by manufacturer. The loss can be total (no response) or intermittent (corrupted or out-of-range signals). The system continuously monitors periodic CAN messages; if a message is not received within the expected time, this DTC is stored.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Faulty window motor (integrated module or separate motor, depending on design)
- Open, short, or excessive resistance in the CAN high (CAN-H) or low (CAN-L) bus wiring to the motor module
- Faulty door control module or BCM acting as gateway
- Damaged, corroded, or disconnected connector in the door harness (critical at the door-to-body junction)
- Faulty CAN bus termination (120 ohm resistors)
- Weak battery or voltage drop affecting module operation
- Corrupted software or need for update in the affected module or master module
3. Symptoms You Will Notice
- Power window for the affected door does not operate
- Window may operate intermittently or slowly
- Other windows or related functions may also malfunction
4. Step-by-Step Diagnosis
Scan for all stored codes and note any related CAN bus or module codes
Inspect the door harness connector at the door-body junction for damage, corrosion, or loose pins
Check CAN bus wiring for opens, shorts, or high resistance using a multimeter or oscilloscope
Verify proper CAN bus termination (60 ohms across CAN-H and CAN-L with power off)
Test the window motor module by swapping with a known-good unit or using a diagnostic tool to command operation
Check battery voltage and charging system; repair if low
Update module software if available per manufacturer service bulletin
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive, but the affected window will not operate. This is a medium-severity issue; you can continue driving until repair.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on whether the issue is wiring, a connector, or a window motor module replacement.