What Does a Reserved ISO/SAE Code Mean?
A reserved ISO/SAE diagnostic code (such as P00C0 to P00FF) often indicates that an electronic system in your vehicle is not meeting the communication standards established by the International Organization for Standardization (ISO) and the Society of Automotive Engineers (SAE), rather than pointing to a specific faulty part.
Understanding the ISO and SAE Regulatory Bodies
ISO (International Organization for Standardization) and SAE (SAE International) are two organizations that define technical standards for the automotive and aerospace industries. Their collaboration has established a set of mandatory guidelines for On-Board Diagnostic (OBD-II) systems since late 1995.
These standards ensure reliable and fast communication between the various vehicle control modules, while minimizing conflicting messages and electromagnetic interference.
The Crucial Role of the CAN Bus
The CAN (Controller Area Network) bus is the main network that allows the Powertrain Control Module (PCM) and the numerous onboard controllers (up to 70 in a modern vehicle) to communicate with each other. When the PCM detects a communication error or non-compliance with ISO/SAE standards on this network, it stores a diagnostic trouble code and may illuminate the Malfunction Indicator Lamp.
Severity and Symptoms of a Reserved ISO/SAE Code
The severity of this code can vary significantly. Therefore, a thorough diagnosis is essential.
Possible Symptoms
- A multitude of unpredictable driving symptoms
- No apparent symptoms (intermittent fault)
- Presence of other associated diagnostic trouble codes
Potential Causes
- Damaged wiring or loose/corroded connector
- Faulty electronic control module
- Programming or software issue in a control module
- Electrical power supply problem (weak battery, alternator)
Diagnostic Procedure
Diagnosing a reserved ISO/SAE code can be complex. Here is a recommended procedure:
- Check and repair any other stored diagnostic trouble codes as a priority.
- Consult the applicable Technical Service Bulletins (TSBs) for your vehicle.
- Visually inspect all CAN bus wiring and connectors for damage, corrosion, or signs of rodent activity.
- Check the battery state of charge and the terminal connections. Low voltage can trigger this code.
- Use a professional OBD-II scanner to read freeze frame data and clear the codes. Test drive the vehicle to see if the fault reappears.
- Perform a wiggle test on wiring harnesses and connectors while the engine is running to identify an intermittent problem.
Examples of Reserved ISO/SAE Codes
P00C0, P00C1, P00C2, P00C3, P00C4, P00C5, P00C6, P00C7, P00C8, P00C9, P00CA, P00CB, P00CC, P00CD, P00CE, P00CF, P00D0, P00D1, P00D2, P00D3, P00D4, P00D5, P00D6, P00D7, P00D8, P00D9, P00DA, P00DB, P00DC, P00DD, P00DE, P00DF, P00E0, P00E1, P00E2, P00E3, P00E4, P00E5, P00E6, P00E7, P00E8, P00E9, P00EA, P00EB, P00EC, P00ED, P00EE, P00EF, P00F0, P00F1, P00F2, P00F3, P00F4, P00F5, P00F6, P00F7, P00F8, P00F9, P00FA, P00FB, P00FC, P00FD, P00FE, P00FF.
Need help diagnosing a trouble code on your vehicle? Consult a qualified mechanic with the appropriate diagnostic tools to avoid any risk of damaging the control modules.