SAP / SAI Delete Solutions — Secondary Air Injection Removal

Secondary Air Injection — the SAP or SAI system fitted to most petrol engines built between 2002 and 2018 — is one of the most reliable causes of expensive workshop visits. Designed to inject ambient air into the exhaust during cold-start to help the catalytic converter reach light-off temperature faster, the system relies on an electric pump, control valves, and ducting that all live in one of the harshest environments on the car. Failures are common, expensive, and trigger limp-home mode.

For off-road, motorsport, export and pre-emissions-mandate vehicles, our SAP/SAI delete eliminates the system at ECU level. No DTCs, no warning lights, no compromised drivability.

What is SAP / SAI and why is it fitted?

When a cold petrol engine starts, the catalytic converter is below its operating temperature and ineffective at processing emissions. Manufacturers fit a Secondary Air Injection pump to spray ambient air into the exhaust upstream of the catalyst for the first 30-120 seconds after a cold start. This extra oxygen helps the catalyst light off faster, reducing cold-start hydrocarbon emissions during emissions testing cycles.

The system consists of an electric pump (usually mounted in the engine bay), one-way check valves, vacuum-actuated combination valves, hoses, and ECU-driven solenoids. All these components live near hot engine bay temperatures and see infrequent but high-stress duty cycles.

Why SAP / SAI systems fail

• Pump seizure from corrosion. The pump only runs for a few seconds per cold start. Between uses it sits idle, often filling with condensate, which corrodes the impeller and bearings.
• Combination valve sticking. The valve that opens to admit air can stick closed (DTC, no air flow) or open (allows exhaust gas back into the pump, destroying it).
• Check valve failure. When the one-way check valve fails, hot exhaust gases reach the pump and burn out the motor.
• Vacuum line cracks. The control vacuum lines age and crack — the valves stop operating reliably.
• Cold start rattles. A failing pump makes a distinctive metallic rattle on cold start — a common symptom.
• Pump replacement costs. €400–€1,200 depending on vehicle, often requiring intake or bumper removal for access.

Symptoms of SAP / SAI trouble

• Cold-start metallic rattle from the engine bay
• DTCs: P0410, P0411, P0412, P0413, P0414, P0418, P2440, P2444 (all SAP/SAI-related)
• MIL (check engine light) on
• Failed emissions test for cold-start hydrocarbons
• Limp-home mode triggered by combined fault codes
• Audible pump running long after cold start is complete

The off-road / motorsport delete solution

For vehicles used off-road, in motorsport, for export, or in restoration of pre-emissions-mandate cars, an SAP/SAI delete addresses the cost and reliability issues at their source. The process:

1. ECU calibration: The engine map is rewritten to disable the cold-start air injection routine, ignore the related sensors, and prevent fault-code logging.
2. Physical disconnection: For most ECUs, the SAP/SAI pump or actuator plug must be physically disconnected after the file is flashed. This prevents any residual electrical current reaching the failed pump.
3. Optional hardware removal: The pump, valves, and ducting can be removed entirely for weight saving or engine-bay cleanup — not required for the delete to function.

The result: cold starts are consistent, no warning lights, no DTCs, no audible pump rattle, and no expensive pump replacements down the line.

Legal use

SAP/SAI delete affects cold-start emissions only and is illegal for use on the public highway in jurisdictions with cold-start emissions testing. BoostCo provides this solution strictly for off-road, motorsport, export, and restoration applications. The customer is responsible for ensuring their use complies with local laws.

How to order

Read your vehicle's original ECU file using a compatible tuning tool (KESS3, K-TAG, Autotuner, MPPS, Dimsport or similar), submit via the A.R.C.H.I.E. portal or email with your vehicle details. Files are typically returned within 5 minutes via the portal. Need ECU compatibility checked first? Get in touch.

Related solutions

• Cold Start Noise Reduction
• DTC / SPN Code Removal
• EVAP System Removal