BMW 2796 — Secondary-Air Pump Relay
- Severity
- Informational
- Module
- DME
- OBD-II Code
- P1411
Description
Fault code 2796 relates to the secondary air injection pump relay control circuit. The secondary air injection system pumps ambient air into the exhaust manifold during cold starts to accelerate catalytic converter warm-up and reduce emissions. The DME activates the pump relay during the first seconds after a cold start, and monitors whether the pump actually responds. This code is set when the DME commands the relay on but detects no pump activity.
The DME commanded the secondary air injection pump relay to activate during a cold start, but detected no activity from the pump. The monitoring occurs during the first 1–2 cold start events and requires onboard voltage above 10V. An open circuit in the relay's control activation circuit prevents the relay from energizing, so the pump never runs. The fault is recorded within 5 seconds of detection.
2796 - P1411: Secondary-Air Pump Relay - No activity detected
Symptoms
The emissions warning lamp (MIL / check engine light) illuminates — ECE and US market vehicles both light the MIL for this fault. A CC message is displayed. No electronic engine power reduction is applied and no driveability symptoms occur. The secondary air system only operates briefly during cold starts, so the driver will not notice any performance difference. The vehicle will fail an emissions inspection with this code present.
Common Causes
- Open circuit in the relay control wire between the DME and the secondary air pump relay. The wire may be broken, chafed through, or have a corroded connection at either end.
- Failed secondary air pump relay. The relay's coil may be open-circuit internally, preventing it from energizing when the DME provides the ground signal.
- Corroded or loose connector at the relay socket or at the DME connector. The relay socket in the fuse box is exposed to moisture on some platforms.
- Failed DME output driver. In rare cases, the DME's internal relay driver transistor has failed. This would typically affect only this one output.
- Seized secondary air pump. If the pump has seized mechanically, the relay may energize but the current draw pattern is abnormal, which some DME software versions interpret as no activity.
Diagnosis Steps
- Locate the secondary air pump relay — on most platforms it is in the engine bay fuse/relay box. Refer to the fuse box diagram for your specific chassis.
- Remove the relay and inspect the socket for corrosion, burnt contacts, or debris.
- With the relay removed, use ISTA or INPA to activate the relay output. Measure voltage at the relay socket control pin (DME-side) — you should see battery voltage toggling when the test is activated. No voltage indicates a DME output driver fault or broken wire from the DME.
- Test the relay separately: apply 12V to the relay coil pins and verify the contacts close (audible click and continuity across the load pins).
- If the relay is good, check the wire between the DME relay output pin and the relay socket for continuity. Also check the connector at the DME end.
- Check the pump itself — with a known-good relay installed, trigger activation via ISTA and listen for pump operation. If the relay clicks but the pump does not run, the pump motor has failed or seized.
Resolution
Repair any broken or corroded wiring. Replace the relay if it has failed. If the pump motor has seized or failed, replace the secondary air pump. Clear the fault code. Verify the repair by performing a cold start (vehicle must be fully cooled) and checking that the MIL does not return after two consecutive drive cycles. This is a DIY-accessible repair — the relay is in the fuse box and the pump is typically mounted in the engine bay.