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Air injection reaction pump – Taurus Sable.

Fix Air injection reaction pump – Taurus Sable

P1414, P1413, P0401, P0402, air injection reaction pump, AIR, Ford Taurus, Mercury Sable.

The P1414, P1413, P0401, P0402 code relate to the air injection reaction pump (AIR). The purpose of this pump is to inject air directly into the exhaust manifold to complete the combustion process. At cold startup, the computer commands a rich mixture. The extra air from the AIR pump oxidizes the extra hydrocarbons and carbon monoxide in the exhaust during this rich mixture period. The AIR pump is active only during the first 20-120 seconds of engine operation, or until the catalytic converter heats up.

The PCM monitors the effectiveness of the AIR pump by watching the O2 sensor. So you start the cold engine. The PCM sees it’s cold by checking the engine coolant temp sensor. If it’s below 195°, it’s “cold.” The PCM commands a rich mixture. The PCM power the AIR pump relay to switch power to the pump (electric pump draws high current, so it needs a relay to switch the power). Extra air blows into the exhaust and PCM starts a timer. If the O2 sensor doesn’t show a lean condition within the time limit, it figures the pump isn’t working and sets a P0411 secondary air injection system flow (low flow or no flow) malfunction. The PCM activates the AIR relay by providing ground to the control coil. The PCM checks for faults on the control coil side of the AIR relay, and sets a P0412 secondary AIR circuit malfunction if it finds one. The problem can be an open in the wire from the relay to the PCM, no power into the control coil from fuse 128, or an internal “driver” fault within the PCM that won’t provide ground to the relay control coil.

Once the AIR relay is activated, the PCM checks voltage on the power feed to the AIR pump. If it detects a problem on the secondary side of the relay, it sets one of two codes; a P1413 secondary air injection system monitor circuit low, or P1414 secondary air injection system monitor circuit high.

The AIR pump is an electric pump. So when the relay contacts close and provide power to the AIR pump the PCM monitors the power feed and expects to see extremely low voltage (less than 1-volt–basically just voltage drop). When PCM tells the relay to shut off, it opens the contacts. If the PCM sees battery voltage on the feed to the AIR pump when the relay is ON, there’s either an open between the relay and the pump, bad relay, bad relay connector, PCM fault, or the pump is dead (that circuit isn’t using power)—P1414. If the PCM sees low voltage on the power feed to the AIR pump when the relay is OFF, there’s a short somewhere providing power to the pump, bad relay, faulty air pump, or PCM fault.

© 2012 Rick Muscoplat

Posted on by Rick Muscoplat


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