What Does U1243 Mean?
Duplicate of U1242, indicating another module or the same module is experiencing exterior environment data loss. Multiple codes suggest either multiple sensor failures or a communication problem affecting the entire exterior sensor network.
Common Causes
30%
Multiple exterior sensor failures or shared power/ground issue
25%
Body control module failure affecting multiple sensor inputs
25%
Damaged harness affecting multiple exterior sensor circuits
15%
SCP bus communication failure in environmental sensor network
5%
Blown fuse or relay affecting multiple sensor circuits
Diagnostic Steps
1
Step 1: Compare U1242 and U1243 to determine if set by same or different modules
2
Step 2: Check power and ground supply to all exterior environmental sensors
3
Step 3: Inspect front wiring harness and connectors for damage from water intrusion or collision
4
Step 4: Test each exterior sensor individually to identify multiple failures versus wiring issue
5
Step 5: Address common power/ground/communication issue if multiple sensors are affected simultaneously
Estimated Repair Cost
$150 - $600
Parts + labor, varies by vehicle and location
Duplicate of U1242, indicating another module or the same module is experiencing exterior environment data loss. Multiple codes suggest either multiple sensor failures or a communication problem affecting the entire exterior sensor network.
The most common cause of U1243 (SCP (J1850) Invalid or Missing Data for Exterior Environment) is: Multiple exterior sensor failures or shared power/ground issue
Typical repair costs for U1243 range from $150 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Minimal safety concern. Automatic climate and lighting features may be compromised, but core vehicle operation and safety systems are not affected.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1243 to identify the root cause.
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Quick Info
Category
Network
System
HVAC / Body Control / Lighting
Difficulty
Type
Manufacturer
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