How is fault code P0411 fixed?

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Start the car stone cold first thing in the morning and listen at the pump. If you hear nothing, the fault is likely electrical or the pump itself. If you hear it spin but still get the code, suspect a blocked valve or hose 2. Command the pump on with a scan tool, key on and engine off, and check it actually runs. Back this up by checking the relay and fuse if it stays silent 3. Pull the air hoses and inspect for splits, soot, and disconnection. Have a good look at the vacuum line and solenoid feeding the combi valve 4. Pop the combi valve off and check it for carbon. They cake up solid and stop the air passing, a very frequent finding on high-mileage cars 5. Watch the front oxygen sensor voltage while the pump runs. A working system shows the reading go lean as fresh air hits the exhaust. No shift means the air isn't getting there 6. Read any other stored codes before condemning parts, as a vacuum or wiring fault can cause this without the pump being dead

Secondary Air Injection System Incorrect Flow Detected

Jump to the fix

Severity

Low

Can I keep driving?

Usually drivable; have it fixed at the first opportunity.

First step

A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training. 1. Start the car stone cold first thing in the morning and listen at the pump. If you hear nothing, the fault is likely electrical or the pump itself. If you hear it spin but still get the code, suspect a blocked valve or hose 2.

PPowertrain
0Generic code
4Emissions
11Sequence number

What does it mean?

The secondary air injection (AIR) system aids in reducing hydrocarbon (raw fuel) tailpipe emissions during a cold start. An electric air pump draws fresh air and pumps it into the exhaust in order to accelerate catalytic converter operation. A secondary air injection pressure sensor is used by the Powertrain Control Module or PCM to monitor the air flow from the air injection pump.

The PCM supplies 5 volts to power the sensor and another 5 volts as a reference or signal while finally supplying the much needed ground on the third circuit. The sensor returns a certain amount of the reference voltage based upon the amount of pressure changes within the exhaust system. Code P0411 will set when the predicted system pressure and actual system pressure is above a predetermined amount for a certain amount of time (for example; above .4 volts for 22 seconds).

This amount is set by the manufacturer.

Symptoms

Likely causes

How to fix it

Codes From the Same System

All Fault Codes

Related Similar Codes

This information follows the generic OBD-II definition and does not replace a vehicle-specific diagnosis. The severity rating is rule-based; an authorised diagnostic reading is required for a definitive answer.