Understanding ISO/SAE Reserved Fault Codes (P016A to P016F)
ISO/SAE reserved fault codes, such as P016A, P016B, P016C, P016D, P016E, and P016F, indicate a communication problem within your vehicle’s network. Unlike a faulty component, this code often signals that a system is not meeting the communication standards established by the International Organization for Standardization (ISO) and the Society of Automotive Engineers (SAE). Diagnosing this issue requires understanding these standards and their impact on your car’s network.
What are ISO and SAE?
SAE International (Society of Automotive Engineers) is an American organization founded in 1905 that develops standards for the automotive and aerospace industries. You might know the term “SAE” in reference to standard (non-metric) tools or threads.
The International Organization for Standardization (ISO), established in 1947, is a global federation that promotes uniformity in technological and economic fields to facilitate international trade. It particularly excels in data communication and information technology standards.
The Role of ISO/SAE in Your Vehicle
Since late 1995, manufacturers have collaborated with ISO and SAE to establish a set of mandatory guidelines for On-Board Diagnostic systems (OBD-II) and data communication. These standards cover:
- Fast and reliable message delivery.
- Minimizing conflicting messages.
- Reducing electromagnetic noise.
- Cost-effectiveness of systems.
Automotive protocols subject to these standards include the CAN bus (Controller Area Network), DC bus, Keyword Protocol, LIN (Local Interconnect Network), and VAN (Vehicle Area Network).
Focus on the CAN Bus
To diagnose an ISO/SAE reserved code, let’s focus on the CAN bus. It is a vast network of wires and connectors that allows the Powertrain Control Module (PCM) and up to 70 other onboard controllers to communicate instantly and simultaneously.
When the PCM detects an interface error in one of these controllers or in the CAN network itself – indicating non-compliance with ISO/SAE guidelines – it stores a fault code (P016A-P016F) and may illuminate the Malfunction Indicator Lamp.
Severity and Symptoms of ISO/SAE Codes
The severity of an ISO/SAE reserved code varies considerably. The condition can be serious or completely inconsequential, making its diagnosis potentially frustrating.
Possible Symptoms:
- Virtually any drivability issue (stalling, power loss, etc.).
- No noticeable symptoms (intermittent code).
- The presence of other Diagnostic Trouble Codes (DTCs) is a crucial clue.
Potential Causes of the Fault
- Electrical Problems: Damaged wiring (especially by rodents), corroded or loose connectors.
- Power Issues: Weak or faulty battery, alternator not charging properly.
- Controller Failures: A faulty onboard controller.
- Software: A programming error or outdated software in a controller.
Step-by-Step Diagnostic Procedure
Diagnosing an ISO/SAE reserved code relies heavily on the presence of other codes and symptoms. Here is a step-by-step approach:
- Diagnose Other Codes First: Always repair any other stored fault codes before addressing the ISO/SAE code.
- Consult Technical Service Bulletins (TSBs): Look for TSBs matching your vehicle, its symptoms, and its codes. An applicable TSB can greatly simplify diagnosis.
- Check Electrical Power: Clean the battery terminals, ensure it is fully charged, and that the alternator is producing correct voltage (approximately 13.5-14.5V). Low voltage is a common cause of communication problems.
- Thorough Visual Inspection: Inspect all visible CAN network wiring and connectors. Look for signs of damage, corrosion, or rodent nests. Repair or replace damaged components.
- Use an OBD-II Scanner:
- Connect a scanner and record all stored codes and freeze frame data.
- Clear the codes and perform a road test to see if the code returns immediately or intermittently.
- Wiggle Test: If the code persists, perform a wiggle test on the controller and CAN bus connectors while the engine is running to reproduce an intermittent fault.
- Faulty Controller: If all wiring and power are good, a faulty onboard controller or one requiring a software update is a likely cause.
Conclusion and Call to Action
ISO/SAE reserved codes (P016A-P016F) can be complex to diagnose due to their often intermittent nature and varied causes. A methodical approach, starting with a visual inspection and checking electrical basics, is essential.
Suspect a CAN network problem or need professional help? Don’t let an illuminated check engine light worry you. Consult a qualified mechanic with the appropriate diagnostic tools to efficiently identify and resolve the root cause of this code.