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P codepowertrainMedium severity

P2436Secondary Air Injection System Air Flow/Pressure Sensor Circuit Range/Performance (Bank 2)

The Bank 2 secondary air injection air flow/pressure sensor is reporting values that don't match what the PCM expects for the commanded pump state.

Definition

During cold starts the PCM runs the secondary air injection pump and expects the Bank 2 air flow/pressure sensor to show a distinct pressure rise while the pump is on and near-atmospheric readings when it is off. P2436 sets when the signal stays in range electrically but fails this rationality check—for example, little or no pressure change when the pump runs. Symptoms are usually limited to the MIL and an emissions-test failure, though a rough cold idle or hissing pump noise can accompany a genuinely restricted system.

Common causes

  • Carbon-blocked or stuck Bank 2 air switching/check valve preventing normal pressure changes
  • Restricted or leaking SAI hose or metal pipe on the Bank 2 side
  • Weak secondary air pump delivering low flow
  • Drifted or soot-contaminated SAI pressure sensor
  • Blocked air injection passages in the Bank 2 cylinder head or manifold
  • Faulty vacuum supply or solenoid controlling the Bank 2 switching valve

Common misdiagnoses

  • Air pump replaced when the switching valve or passages are blocked
  • Sensor replaced without checking for blocked check valves or passages
  • Both banks' valves replaced when only the Bank 2 side is at fault
  • Exhaust manifold or catalytic converter suspected without testing the SAI plumbing

Troubleshooting steps

  1. 1.Compare Bank 1 and Bank 2 sensor PIDs

    On a cold start, both banks should show a similar pressure rise when the pump runs; a flat Bank 2 reading isolates the fault to that side.

  2. 2.Command the SAI system with a scan tool

    Activate the pump and switching valves bidirectionally while watching the Bank 2 sensor; note whether pressure responds to each commanded state.

  3. 3.Inspect Bank 2 hoses and valve

    Remove the Bank 2 switching/check valve and look for carbon buildup, moisture damage, or a stuck valve plate; verify hoses aren't collapsed or split.

  4. 4.Check passage flow

    With the valve removed, blow low-pressure air through the injection passages; heavy restriction from carbon means the head passages need cleaning.

  5. 5.Verify pump output

    Run the pump and confirm strong airflow at its outlet hose; a weak or noisy pump with water inside should be replaced along with fixing the moisture source.

  6. 6.Test or substitute the sensor

    If flow and valves check good, verify the sensor reads atmospheric baseline correctly key-on engine-off and replace it if biased.

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