Serial Communication Link Malfunction
The P0600 code means the vehicle's onboard diagnostic system has detected: Serial Communication Link Malfunction. This is a serious severity code.
- Keep driving?
- Limited driving only
- DIY difficulty
- medium
- Estimated cost
- $100-$250 for battery; $200-$600+ for wiring or module diagnosis
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Common Symptoms
- Multiple warning lights on dashboard
- Communication errors between control modules
- Various system malfunctions (transmission, ABS, body control)
- Vehicle may enter limp mode
Probable Causes (Ranked by Likelihood)
- Low system voltage causing CAN bus communication errors High
- Damaged CAN bus wiring or connector High
- Faulty control module dragging down the CAN bus Moderate
- Corroded ground connections affecting module communication Moderate
Frequently Asked Questions
Can a bad battery cause P0600?
Yes. Low or unstable voltage is a very common trigger for serial communication codes. Always check the battery and charging system before pursuing expensive module or wiring repairs.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Check battery voltage and charging system first: low voltage is the most common cause of serial communication errors.
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Inspect CAN bus connectors and wiring under the hood and at the data link connector (OBD-II port) for damage.
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Scan all modules for additional codes. A failing module will often set codes in multiple systems.
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Test CAN bus resistance between pins 6 and 14 of the OBD-II port: should be approximately 60 ohms (two 120-ohm terminating resistors in parallel).
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- Any vehicle: most common when battery is low or failing
- Ford vehicles (CAN bus issues on early 2000s)
- GM vehicles
Related Codes
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