P015E and P015F: Understanding and Diagnosing ISO/SAE Reserved Codes
The fault codes P015E and P015F are known as “ISO/SAE reserved codes.” Unlike many other OBD-II codes that directly point to a faulty component (such as an oxygen sensor or an injector), these indicate a communication problem between the various electronic modules in your vehicle. They signal that the communication standards established by the International Organization for Standardization (ISO) and the Society of Automotive Engineers (SAE) are not being met.
What are ISO and SAE?
SAE International is a US-based organization, founded in 1905, that develops standards for the automotive and aerospace industries. The ISO (International Organization for Standardization), established in 1947, is a worldwide federation that promotes technological uniformity to facilitate international trade. Together, they have defined a set of strict protocols to ensure reliable and error-free communication between the dozens of onboard computers in a modern vehicle, via the CAN Bus (Controller Area Network).
How Severe are P015E and P015F Codes?
The severity of these codes is highly variable. It can range from an intermittent problem with no apparent symptoms to a complete vehicle breakdown. It all depends on which module or modules are no longer communicating correctly. Therefore, it is essential not to ignore these codes.
Symptoms of ISO/SAE Reserved Codes
- Illuminated Check Engine Light (MIL)
- Drivability issues (loss of power, stalling)
- Various electrical malfunctions (gauges, air conditioning, etc.)
- No noticeable symptoms (the code is stored intermittently)
- Presence of other concurrent fault codes
Possible Causes
- Wiring problems: Cut wires, oxidized, loose, or damaged connectors.
- External damage: Rodent nests having chewed through cables.
- Electrical issues: Weak battery, faulty alternator, poor grounds.
- Module failure: Faulty control module (PCM, BCM, etc.).
- Software programming error: Bug requiring a software update.
Diagnostic Procedure
- Read all codes: Using an OBD-II scanner, retrieve and note all stored codes. Always diagnose and repair other codes first.
- Check TSBs: Consult the manufacturer’s Technical Service Bulletins (TSBs) for known issues with your specific vehicle model.
- Visual inspection: Meticulously inspect all CAN bus wiring and connectors, paying close attention to signs of rodent damage, corrosion, or debris.
- Check electrical state: Verify battery voltage (engine off and running) and the quality of the connections at the terminals.
- Wiggle test: With the engine running, gently shake wire harnesses and connectors to reproduce an intermittent problem.
- Advanced diagnostics: If the previous steps yield no results, using an oscilloscope to analyze the signal waveforms on the CAN High (CAN-H) and CAN Low (CAN-L) lines is often necessary to identify a failing module.
Examples of Other ISO/SAE Reserved Codes
P011E, P011F, P016A-P016F, P017A-P017F, P04AB, P030A, P052F, P056E, P025E, P025F, etc. The diagnostic procedure is similar for all these codes.
Conclusion and Call to Action
Diagnosing a P015E or P015F code can be complex due to its systemic nature. A rigorous methodology, starting with a thorough visual inspection and verification of electrical basics, is paramount.
Do you have a Check Engine Light on and suspect a communication problem? Don’t let the issue worsen. Share the exact codes and your vehicle model in the comments below for more specific advice, or consult a mechanic specialized in electronic diagnostics for an in-depth diagnosis with appropriate equipment.