Comprehensive diagnostic guide for OBD-II code P1414

Topic: Secondary Air Injection System - Supervisor Input High (P1414)

Background and code context

• What the code represents: P1414 is associated with the Secondary Air Injection (SAI) system. The open-source definition linked to this code describes it as a "Secondary Air Injection supervisor input high," i.e., the SAI supervisory circuit is reporting a higher-than-expected input signal than the control module anticipates. This points to an electrical or control issue rather than a simple mechanical failure alone.
  • Source alignment: Open Source code definition titled "Secundária Supervisor injeção de ar - sinal de entrada alto."
• Where this fits in the OBD-II framework:
  • OBD-II uses Diagnostic Trouble Codes (DTCs) to flag engine/emanations-related concerns; codes are organized as Powertrain Codes among other categories.
  • Emissions-related monitoring relies on these codes to indicate faults that could affect emissions.
• Practical takeaway: P1414 indicates a fault condition in the SAI subsystem that is detected by the ECU's supervisor/monitor logic, usually manifesting as an abnormal signal on the SAI control input or a fault in the SAI circuit rather than being purely a performance fault of the mechanical SAI hardware alone.

System overview (what the Secondary Air Injection system does)

• Purpose: The SAI system introduces ambient air into the exhaust to promote oxidation of exhaust hydrocarbons during cold-start and certain operating windows, aiding emissions reduction.
• Key components commonly involved (high-level view):
  • SAI pump (air delivery device)
  • Valves or diverter valves that route air into the exhaust
  • Check valves and associated vacuum/air lines
  • Wiring and control circuits that feed the supervisor/ECU signals
• The ECU/engine control monitor checks the status of the SAI circuit (pump, valve, and associated sensors) and flags faults when an abnormal input is detected, including when a signal is higher than expected.

Symptoms

• The Malfunction Indicator Lamp (MIL) is illuminated (check engine light) with P1414 stored or pending.
• Emissions-related readiness tests fail or cannot be completed during diagnostic testing.
• Some vehicles may not exhibit obvious driveability issues, but cold-start emissions behavior can be abnormal, or there can be intermittent SAI activity indications.
• In some cases, a vehicle may display multiple SAI-related codes or related DTCs in conjunction with P1414.

Probable Causes

Note: Specific vehicle data may shift these probabilities. Without a NHTSA data set , use these as practical bets based on common field observations and the nature of the SAI circuit.

• Wiring/connector faults affecting the SAI supervisor input line (high resistance, open circuit, shorts to battery or other lines, corroded pins): relatively common
  Likelihood: moderate to high (roughly 25-40%)
• Faulty SAI pump or failed/diverted valve (stuck open, stuck closed, or non-responsive): common cause when the mechanical path is involved
  Likelihood: moderate (roughly 15-30%)
• Vacuum/air line leaks or degraded check valves in the SAI plumbing: can cause unexpected signals or reduced performance
  Likelihood: low to moderate (roughly 10-25%)
• Relay or circuit power/ground supply issues to the SAI pump/valves: possible, especially on older systems
  Likelihood: low to moderate (roughly 5-15%)
• PCM/ECU fault or software-related issue (less common, but possible in rare cases or after software/firmware updates)
  Likelihood: low to moderate (roughly 5-10%)
• Other mechanical issues (e.g., clogged lines, blocked check valve, manufacturing defect) and incidental causes
  Likelihood: variable (roughly 5-15%)

Important Notes

Diagnostic Approach

Goal: Confirm P1414 is valid, identify whether the issue is electrical, mechanical, or ECU-related, and perform targeted repairs.

1) Confirm code and collect data

• Use a good scan tool to verify P1414 is current and to review:
  • Freeze frame data (engine temperature, RPM, SAI-related sensor values if available)
  • Any related DTCs (other P14xx codes, SAI-related codes, or fuel/air sensor codes)
  • SAI readiness/monitor status if the tool supports it
• Check service information for manufacturer-specific definitions of P1414 for this vehicle (the open-source mapping notes "Secondary Air Injection supervisor input high" as a potential interpretation).

2) Visual and basic electrical inspection

• Inspect physical SAI components and routing:
  • SAI pump (if present on the vehicle), hoses, check valves, diverter valves, and any mounting hardware
  • Vacuum lines or pressure lines for cracks, disconnections, or leaks
  • Electrical connectors and wiring harnesses to the pump/valves/pressure sensors
• Look for signs of prior repairs, corrosion, or damaged grounds.
• Verify battery voltage is stable; a weak battery can cause sensor/pump misreads or intermittent signals.

3) Electrical/system signal checks

• With key on (engine off) or during a run, measure the input signal line(s) for the SAI supervisor as indicated by the vehicle's service information or appropriate wiring diagrams:
  • Check for proper voltage reference, ground integrity, and absence of shorts to supply voltage
  • Look for an input that is abnormally high when the SAI should be idle or inactive; or a signal that does not respond to known commands
• Inspect the input circuit for:
  • Broken wire or loose connector
  • High-resistance path or corrosion
  • Short to power, short to ground, or cross-wiring with other circuits
• If a dedicated SAI circuit test feature exists on your scan tool, perform it to observe pump/valve activation and response.

4) Functional/mechanical verification

• Command the SAI system (via scan tool or service procedures) to:
  • Activate the SAI pump (and/or the diverter valve) and verify that the device responds
  • Confirm that the expected current draw or electrical signal corresponds to the pump/valve operation
• Listen for pump operation (if accessible) and observe any audible changes when the system is commanded
• Confirm that the SAI lines and valves move or switch as commanded (no binding, stiction, or leakage)

5) Leak and integrity testing of plumbing

• Perform a smoke or leak test on SAI lines, check valves, and fittings to locate any leaks
• Inspect the exhaust-end check valve and any routing devices for blockages or leaks that could skew signals

6) Correlation with related systems

• Check for related DTCs that might point to a broader emissions or control issue (oxygen sensor, catalyst efficiency, vacuum system, etc.)
• Ensure that there are no concurrent faults that might mimic or mask P1414 symptoms

7) Repair decision and verification

• If a mechanical fault is found (e.g., failed pump, stuck valve, cracked line):
  • Repair/replace faulty component(s)
  • Re-seat connectors and repair any damaged wiring as needed
• If electrical fault is found (e.g., high-resistance harness, short to voltage, poor ground):
  • Repair wiring, connectors, or grounds
  • If a short to voltage is suspected, isolate and correct the offending circuit
• If all hardware and wiring tests pass but the signal remains "high" in the supervisor input:
  • Consider ECU/PCM fault or software/Calibration issue; compare against service bulletin or vehicle-specific updates
• After repair, clear DTC(s) and re-run the drive cycle to verify that P1414 does not return
  • Ensure the SAI monitor passes (if the vehicle reports readiness for the SAI monitor)

8) Follow-up testing and verification

• Confirm no other SAI-related codes present after repair

• Drive through normal operation to ensure the SAI monitor completes its cycles and the MIL does not reappear

• If the problem recurs, re-evaluate the input line signal integrity and re-check for correlated components or software updates

• Because P1414 is related to the SAI supervisory input, electrical faults (wiring, connectors, or a faulty sensor/actuator) are common culprits, but mechanical faults in the SAI path can contribute to abnormal signals as well.

• The literature notes that DTCs are part of the emissions-monitoring framework; a P1414 fault can affect emissions readiness and testing.

• If you encounter this code in a vehicle where SAI is not present or the system differs (e.g., certain engines without SAI hardware), treat P1414 as a misinterpretation of the code context and verify with OEM data.

Documentation

• Symptoms observed and the exact DTC (P1414) with any related codes
• All tests performed (visual inspections, electrical checks, functional tests, smoke tests)
• Parts replaced (if any) and service actions taken
• Confirmation steps (MIL status, readiness monitor status, and re-test results)

References to support the diagnostic framework

• Diagnostic Trouble Codes and general OBD-II concept: Wikipedia - OBD-II: Diagnostic Trouble Codes; the article explains how DTCs are used in modern automotive systems to monitor parameters and trigger codes.
• Powertrain codes and their role in OBD-II: Wikipedia - OBD-II: Powertrain Codes; explains that powertrain codes cover emissions-related and engine-control concerns.
• Emissions testing and the role of OBD-II monitors: Wikipedia - OBD-II: Emissions Testing; describes how OBD-II monitors participate in emissions readiness and testing.
• Specific code interpretation mapping (secondary air system): Open Source definition titled "Secundária Supervisor injeção de ar - sinal de entrada alto"; provides the mapping for P1414 as "Secondary Air Injection supervisor input high."

For reference:

• The exact P1414 interpretation in your vehicle may vary; the open-source mapping provides a practical description that aligns with the general concept of an elevated supervisor input for SAI.

Safety Considerations

• Disconnect power only when performing mechanical disassembly or wiring work on the SAI hardware; observe proper lockout/tagout practices.
• When performing leak testing (smoke tests), follow manufacturer guidelines and ensure the vehicle is in a safe testing environment.
• Avoid inhaling exhaust or smoke test by ensuring proper ventilation and PPE as needed.

This diagnostic guide was generated using verified reference data:

• Wikipedia Technical Articles: OBD-II
• Open-Source OBD2 Data: N/A (MIT)

Content synthesized from these sources to provide accurate, real-world diagnostic guidance.

---