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Secondary Air Pump Failure

Hi all,

I have a PZEV (Partial zero emission vehicle) 2006 Focus. Recently, my car threw the check engine light. Looked at the two codes, found out it was for the secondary air system. I pulled the car apart, removed the pump, checked that the pump was indeed receiving 12v (checked with a multimeter) with ignition-on-engine-off. I couldn’t feel, or hear, the pump spinning. Figuring it was the source of the problem (as opposed to a clogged hose), I replaced the relay, thinking that perhaps it was on its dying leg. That didn’t help. I next replaced the pump, which also didn’t help. To tell you the truth, I can’t even hear or feel the new pump running with ignition-on-engine-off.

I “reset” the codes, or so I thought, by disconnecting my battery for quite a few minutes. During the first startup, the check engine light isn’t on. Starting up again though later in the day, the light returns. The engine does run a bit rough when cold without the pump malfunctioning for the first few brief moments.

Anyone have any similar issues or insight? Is the pump supposed to be powered and running for the entire time ignition-on-engine-off (I assume so since it is receiving 12v). How loud should these guys be? I would have thought I would be able to feel the motor spinning or hear something…

Engine running rough is not likely related to secondary air pump. That pump runs only until the engine gets warm and starts to run closed loop, when the secondary air pump turns off.

As you can tell by looking at it, it is substantially similar to a vacuum cleaner fan, and that is pretty much what it sounds like. Should be easy to hear when the hood is open. You can hot wire it with 12 volts to see if it is capable of running.

There should be a check valve in the exhaust manifold that keeps hot exhaust from backing up into the secondary air pump when it is not running. If that check valve fails, you will have hot, wet exhaust blowing through the secondary air pump spinning it backwards. That can destroy a new pump pretty quickly. That is easy to check. Disconnect the hose from the air pump and start the car. If exhaust blows out that hose, the check valve has failed.

A look at the wiring diagram shows that the PCM is connected to the relay output to the air pump. This means with the air pump unplugged you can expect to see a voltage value at the connector that is from the PCM for diagnostic purposes. First check the fuse, then back probe the air pump connector with a neddle or “T” pin with the air pump connected to see if it has power.

Thanks. I’m aware of the checkvalve. I’ll take a look at it. I’m just surprised I didn’t hear the pump (both the old and the new) turn on with both the relay replaced and 12v at the pump connector. The checkvalve is fairly easy to get to, so I suppose it’s worth looking at.

The engine runs rough for a brief moment - hunting basically in RPM, and occasionally stutters. I believe this corresponds to when the air pump should be turned on (it’s when the car is first started in the first few brief moments). I’ve never had this before the CEL.

Thanks - the fuse is good. It was the first thing I verified. Like I said, 12v is at the pump connector. Relay was replaced.

So, small update. Checked out the check valve. It is absolutely pristine. The inlet hose is in great condition, no evidence of exhaust entering. Ran the car with the hose unplugged, no evidence of exhaust escaping and the check valve malfunctioning. Also, cannot feel any air flow from the pump. I’m pretty certain this is an electrical issue, but I’m a bit perplexed as I measured 12v at the pump connector and the relay was replaced.

How is the pump grounded? How many wires are connected to it? If it has a ground wire, that’s how the PCM controls it, by grounding it…

There are only two wires going to the pump.