OBD Code U1105: SCP (J1850) Invalid or Missing Data for Chassis Status Request

Q: What are the symptoms of fault code U1105?

Check Engine Light illuminated, Stability control or ABS warning lights active, Possible loss of traction control function

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What This Actually Means

In plain language — no jargon

Your car's computer can't receive chassis status information from the network bus, like a radio losing its signal. This breaks communication between modules that control stability, braking, and safety systems.

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Symptoms You May Notice

3 known symptoms for this code

Check Engine Light illuminated

Stability control or ABS warning lights active

Possible loss of traction control function

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How Your ECU Detects This

Technical sensor logic and voltage thresholds

The ECU monitors SCP (J1850) bus communication for valid chassis status frames from other modules (ABS, stability control). It expects periodic messages within specific timing windows; missing or corrupted data triggers this code when no valid frames arrive after repeated polling attempts.

Voltage & Parameter Thresholds

Parameter	Normal Range	Fault Condition
SCP Bus Message Timeout	Valid frame received every 10-100ms	No valid frame for >200ms
Data Validity Check	CRC and counter valid	CRC mismatch or missing checksum

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Diagnostic & DIY Fix Guide

Check these in order — from cheapest to most complex

1

OBD-II Scanner

Clear the code and monitor if it returns; intermittent faults often resolve after a restart.

2

Battery and Terminals

Clean corrosion from battery terminals and ensure secure connections to restore bus voltage stability.

3

J1850 Bus Wiring Harness

Inspect wiring near the PCM and module connectors for chafing, pinches, or loose connections along the SCP bus.

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When to See a Professional Mechanic

Not all fault codes are safe to DIY

Code U1105 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.

Safety note: OBD-II codes identify the system or circuit where a fault was detected — they do not always identify the exact failed component. A professional mechanic using live sensor data will diagnose the root cause more accurately than replacing parts based on the code alone.

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How to Clear Code U1105

What happens after you fix the fault

Once the fault is repaired, U1105 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.

✅ Safe to Clear When

Fault has been diagnosed and repaired
You want to confirm the repair worked
Code appeared after a sensor was cleaned

⚠️ Do Not Clear When

Preparing for an emissions/PUC test
Root cause is still undiagnosed
Check engine light is flashing

Emissions test note: Clearing codes resets OBD readiness monitors. Most vehicles need 50–100 km of mixed driving before monitors complete. Do not clear codes immediately before an emissions or PUC inspection.