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P0410 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


P0410 – Secondary Air Injection System Malfunction


P0410 is an OBD-II generic code that the engine control module (ECM) detected the engine O2 sensor did not detect an increase in the O2 level in the exhaust when the air injection system was commanded on during an active test.

To put it in simplified terms, your car’s computer didn’t get a signal from the oxygen sensor that monitors oxygen content in engine exhaust. Your engine needs both air and fuel to cycle, so having this sensor functioning is fairly important if you don’t want the fuel system dumping too much or too little fuel into the mixture for each engine cycle from faulty readings.


When you get an airflow reading problem code back on your scanner, there are typically few causes: system blockage, faulty sensors, or loose connections. Here’s a rundown of specific PO410 OBDII code causes for most cars:

  • A blocked air injection system intake, constricting exhaust airflow.
  • O2 sensors are wearing out or faulty, causing them to fail, send incorrect readings, or respond slowly to ECM commands.
  • The catalyst is partially clogged, resulting in a back pressure increase on the exhaust end of the airflow.
  • Relay contacts in the air injection pump are not making solid contact


Knowing what to look and listen for can make all the difference when diagnosing the cause of a trouble code. Here are the symptoms most commonly associated with PO410:

  • Check Engine Light is illuminated, and the code is logged in the data freeze-frame.
  • You may hear noises coming from the air injection pump due to worn out bearings
  • The engine may run too rich if excessive O2 is being pumped into the exhaust. You’ll typically notice this symptom when your gas tank starts to empty faster than usual.


Here’s the process a certified automotive technician will use when diagnosing the cause of a PO410 trouble Code:

  • Plug in an OBDII scanner, scan codes and document the freeze-frame data to verify the problem.
  • Use the OBDII tool to clear all engine codes and retest to verify the air injection system is operating properly
  • If other trouble codes have come up during the diagnosis, the technician will attempt to address or repair those issues before continuing with code P0410 diagnosis. This includes repairing or replacing O2 sensors.
  • Next, the technician monitors the O2 sensor in real time using a scanner to verify the sensor reacts when the air injection pump is activated. If the sensor is functioning correctly, the sensor should go to below 150 millivolts within 3 seconds of pump activation.
  • Should the sensors take longer than 3 seconds to respond, the technician will replace any sluggish O2 sensors and retests system.
  • After verifying the sensors are not the root cause, the technician checks the air injection relay for power if the pump isn’t turning on. This allows them to determine if it’s a faulty power connection or a failed air injection pump that needs to be repaired.
  • Finally, the technician will use a multimeter to verify the air injection pump is reading the proper resistance between pins of power and ground. That’s a prime indicator of a faulty pump control or a failed pump.

Common mistakes

Everyone misses important items when running diagnostics on an engine system. A little prevention and knowing what to look for can help you avoid these mistakes yourself. Here’s a quick rundown for the easy-to-make mistakes when diagnosing a PO410 trouble code.

Failing to verify proper intake air flow into the air injection pump before replacing the pump for no air pumping out of it. In other words, did you check to make sure air could get into the pump before assuming it’s broken because air isn’t blowing out of it?

Not taking the time to check all connections and wiring around the air injection pump. Burnt or frayed wires cause a significant portion of all part and system failure codes when diagnosing the root cause of a trouble code. It’s extremely important to visually check connections and wiring first to make sure they aren’t the culprit before you replace perfectly functional and expensive car parts.

How serious is this?

This is a serious issue if you care about fuel economy, the environment and local car emission regulations. The air injection pump system is designed to help lower the exhaust emissions, and a PO410 trouble code can cause the vehicle to fail emission testing if the check engine light doesn’t give it away first. Overall though, trouble with your air injection pump shouldn’t affect normal, safe operation of your vehicle. It’s just going to get poor gas mileage and fail your emissions test.

What repairs can fix the code?

One of the following repairs generally fixes this issue.

  • Replacing the air injection pump and power relay (moderately expensive and difficult)
  • Replacing O2 sensors that respond too slow as they age (less expensive and easy)
  • Replacing the air injection pump intake filter clogged with debris (inexpensive and easy)

Related codes

None listed.


If you see this code pop up on your OBDII scanner, check your exhaust airflow system and pump. Look for faulty wiring, clean the air pump intake filter, and test the O2 sensors if you know how. Otherwise, take it to a shop you trust and have them determine the root cause.

P0410 Code – What Does It Mean & How To Fix It