Staff Answer
Oct 01, 2026 - 12:10 AM
You've actually got two separate issues worth addressing independently. But they could be related depending on your vehicle. What year, make, and model are you working with? That said, here's the general fix path:
For the Secondary Air Injection (SAI) pump code, the most common causes are:
- Failed air pump - they're known to burn out, especially on GM and VW/Audi engines. Test the pump directly by applying 12V to see if it runs.
- Clogged or stuck air injection valve - carbon buildup prevents the valve from opening, triggering the code even with a good pump.
- Failed SAI relay or fuse - check these first before replacing the pump itself.
For the Cylinder #1 misfire, work through the basics in order:
- Swap the spark plug and ignition coil from cylinder #1 to another cylinder - if the misfire follows, you've found your culprit cheaply.
- Check the fuel injector on cylinder #1 for proper operation.
- If plug and coil check out, do a compression test on cylinder #1 - low compression points to a deeper engine issue like a worn valve or piston ring.
The possible connection: a faulty SAI system can cause a lean condition that triggers misfires, so fixing the air pump issue first may help the misfire as well. Start there.
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