What does it mean?
P1433 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Secondary Air Injection System Pump Relay Circuit Open .
Symptoms
- MIL on and the secondary air readiness monitor stays incomplete
- Air pump completely silent during cold start
- Elevated hydrocarbon emissions in the first minute after a cold start
- Slightly rough idle when the engine is cold
- No pump response when commanded with a scan tool
Likely causes
- Broken or disconnected wire between the PCM and the relay coil
- Relay missing from its socket or not fully seated
- Internally open relay coil
- Blown fuse supplying the relay coil or the pump feed
- Corroded, burnt or spread terminals in the relay socket
- High resistance ground for the relay circuit
- Harness break where the wiring passes a bulkhead grommet or a repaired splice
How to fix it
- Confirm the relay is present and fully seated, then remove it and inspect the socket terminals
- Measure the relay coil resistance; an infinite reading confirms an open coil
- With the key on, verify battery voltage at the relay coil supply terminal in the socket
- Check continuity of the control wire from the relay socket to the PCM pin
- Test the fuses in both the coil circuit and the pump power circuit
- Perform a voltage drop test on the ground path for the relay and pump
- Repair the open wiring or replace the relay, then confirm the pump runs for the expected period on a cold start