P0419Generic code

P0419 Code: Secondary Air Injection System Relay B Circuit

The P0419 code means the computer found a fault in the circuit of secondary air pump relay B, which exists on vehicles with two pumps or two relays. A relay that does not close leaves the pump dead, and one that sticks closed runs it all the time. Check the fuse, the relay and the connector before you replace the pump.

Severity
Low
Can I keep driving?
Yes, no immediate risk
Estimated cost
$20 to $400
Difficulty
Medium
System
Emissions Control
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0419 code means

The secondary air pump draws a lot of current, so the computer switches it on through a relay. The computer monitors the relay control circuit.

It does that from its own driver transistor. The P0419 code points to an electrical fault in that control circuit. Before you replace the component, check the fuse, the relay, the connector and the wiring, because they are the most common cause.

A relay that does not close leaves the pump stopped. One that sticks closed keeps it running all the time and ends up burning it out. Check the high-current fuse for the pump as well.

Always start with the simplest things: the fuse, the relay and the connector. Then check supply, ground and signal with the component connected, using back-probes, and finally the continuity of each wire to the computer. Replace the component only if all of that checks out.

P0419 code symptoms

  • Check engine light on.
  • Air pump that does not run, or that does not shut off.
  • Continuous noise from the pump.

Likely causes of the P0419 code

  1. Damaged connector. Loose, broken or corroded.
  2. Fuse or relay blown or with worn contacts.
  3. Wiring cut or shorted between the component and the computer.
  4. Failed component. The coil, the motor or the internal electronics are damaged.

How to diagnose the P0419 code step by step

  1. Activate the component with the scan tool and see whether it responds.
  2. Check the fuse and the relay.
  3. Measure the supply at the connector. You should see battery voltage with the key on or when it is activated.
  4. Measure the resistance of the component and compare it with the manual. Check the insulation to ground too.
  5. Check the control wire for continuity and for the absence of shorts.
  6. Swap the relay with an identical one.
  7. Measure the pump current.

How to fix the P0419 code

  • Repair the connector, the wiring or the supply.
  • Replace the secondary air pump relay if it does not respond with correct supply and control.
  • Clear the codes and verify that the monitor completes.

Technical reference data

  • Typical pump current draw: 20 to 40 amps.
  • These are approximate values, so check the manufacturer data for your engine.

Brand-specific notes

P0419 on Toyota

On Toyota vehicles, a pump with water inside often burns out the relay.

P0419 on Lexus

On Lexus vehicles, a pump with water inside often burns out the relay.

Frequently asked questions about P0419

Can I drive with a P0419 code?
Yes. It normally does not affect driving. Repair it before the emissions inspection.
What does the secondary air pump relay do?
The secondary air pump draws a lot of current, so the computer switches it on through a relay. The computer monitors the relay control circuit.
Do I always have to replace the part?
No. Check the fuses, relays, connectors and wiring first.
How much does it cost to fix P0419?
Roughly $20 to $400, depending on whether it is a fuse, a relay or the pump itself. Diagnosing the P0419 code properly first keeps you from paying for parts you do not need.
What does the P0419 code mean?
It is a generic OBD2 code for a malfunction in the secondary air pump relay B circuit, found on vehicles with two pumps or two relays.
Will a P0419 code clear itself?
Only if the fault was a one-time glitch. A bad relay or a damaged connector will bring the code back on the next cold start.

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Questions about the P0419 code

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