SAP Removal – Secondary Air Pump

Secondary air pump (SAP) removal explained

The Secondary Air Injection system injects fresh air into the exhaust ports or manifold during cold start to speed up catalyst light-off and reduce emissions. It typically includes an air pump, a combination/check valve and one or more solenoids or relays. When components fail or the system is removed, the ECU logs DTCs such as P0410–P0419, triggers a MIL and may alter cold-start behaviour.

A dedicated SAP removal calibration disables SAP-specific monitoring and readiness checks so that SAP-related DTCs no longer appear when the hardware is removed or disconnected. Closed-loop fuelling, catalyst monitoring and all other emission and safety strategies remain active.

When to use SAP removal

• After removing or blanking the SAP pump/valve due to failure or custom exhaust configuration.
• Repeated DTCs such as P0410, P0411, P0412–P0419 or SAP readiness stuck on “Not Complete”.
• Track and off-road vehicles where the SAP system is no longer fitted.
• Cold-start surge or noise linked to SAP activation on tuned engines where the hardware is removed.

Technical overview

During a defined cold-start window, the ECU commands the SAP pump and valve based on coolant temperature, ambient temperature and time since start. It expects to observe a distinct lean reaction on the upstream O₂ sensor and, on some platforms, pressure or flow feedback. If the expected pattern is missing or out of range, the ECU sets SAP-related fault codes and flags the SAP monitor as incomplete.

• Inputs: coolant and ambient temperature, time since start, O₂ sensor behaviour and, where fitted, pressure/flow signals.
• Outputs: pump and solenoid commands, valve duty and plausibility timers.
• Diagnostics: electrical faults, stuck valve, insufficient flow, missing or delayed O₂ reaction.

The SAP removal calibration disables only SAP-related routines. Catalyst monitoring, closed-loop operation, knock control and temperature protections remain active.

How it works

1. Assessment: identify SAP implementation and associated DTC groups on your ECU family.
2. Calibration: disable SAP logic and suppress only SAP-related DTCs and readiness tests.
3. Flash & verify: write the modified file and confirm that no SAP faults return and that cold-start behaviour remains stable.

Operational behaviour after SAP removal

Once SAP diagnostics are disabled, the ECU no longer expects airflow or valve movement during the cold-start phase. This prevents false lean detection or delayed O₂ transitions that would otherwise trigger fault codes when the SAP hardware is removed. The engine continues to follow its normal warm-up enrichment, idle control and closed-loop fuelling. On platforms that integrate SAP checks into readiness routines, the SAP monitor will no longer block inspection, and engines with wideband O₂ sensors maintain consistent feedback control without being influenced by the absence of SAP activity.

Compatibility

SAP removal is supported on many petrol ECUs including Bosch, Siemens/Continental, Delphi, Denso and Magneti Marelli. Use the live database below to check coverage. If your software code is missing, you can send your read for evaluation.

Background reading: Secondary air injection – Wikipedia
Related services: Exhaust Flap Removal • Cold Start Noise Reduction

Legal & technical notice

This calibration is intended only for track and off-road applications where SAP hardware has been removed or disabled and where such modifications are allowed by local regulations. It must not be used to bypass emission-system requirements on public roads.

SAP removal does not correct mechanical faults. All other emission-related components (catalyst, O₂ sensors, EVAP, EGR) must remain functional if still installed. Compliance with emission and road-use regulations is the responsibility of the vehicle owner.