P2431

Air Injection System Air Flow/Pressure Sensor Circuit Range/Performance Bank 1

P2431 is a generic OBD-II powertrain diagnostic trouble code: Air Injection System Air Flow/Pressure Sensor Circuit Range/Performance Bank 1. It is logged by the engine control unit when the air/maf monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P2431
Group
Powertrain
System
Air/MAF
Severity
moderate
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What P2431 means

Code P2431 is stored when the powertrain control module (PCM) detects that the voltage or signal from the secondary air injection (SAI) system's airflow or pressure sensor on Bank 1 falls outside the expected operating range, even though the sensor itself has not completely failed. The SAI system pumps fresh air into the exhaust stream during cold starts to accelerate catalytic converter light-off and reduce hydrocarbon emissions — the sensor monitors whether the pump and associated valves are performing as commanded.

The distinction between P2431 and its companion code P2432 is important: P2431 is a range/performance fault, meaning the sensor is producing a signal but its value is implausible or inconsistent with commanded pump operation. A sensor reading that rises when the pump is off, or fails to rise adequately when the pump is on, will trigger this code. Related codes such as P0410, P2432, P2440, or P2444 are often stored alongside P2431 and should be addressed in the correct diagnostic order.

The most common root cause is a failed or clogged one-way check valve that prevents pressure from building correctly, followed by a worn SAI pump that cannot generate sufficient airflow. Wiring faults — particularly corrosion at the sensor connector — can also cause erratic signal values that land in range/performance territory rather than a hard low/high fault. In rare cases a PCM software update is required.

Although P2431 alone rarely causes immediate drivability emergencies, the accompanying SAI system faults often produce rough cold-start idle, increased hydrocarbon emissions, and a failed emissions test.

Common causes

Most-frequently reported root causes when P2431 is logged.

  • 1
    Faulty or clogged one-way check valve preventing pressure build-up
  • 2
    Worn or failing secondary air injection (SAI) pump with insufficient output
  • 3
    Defective or contaminated air flow/pressure sensor
  • 4
    Corroded or damaged wiring and connectors in the sensor circuit
  • 5
    Defective air control solenoid or switching valve
  • 6
    Blocked or collapsed SAI system hoses or passages
  • 7
    Vacuum leaks in the SAI delivery circuit
  • 8
    PCM fault or software requiring update

Symptoms drivers notice

Illuminated Check Engine Light (MIL)
Rough idle or hesitation during cold start
Hard starting in cold weather conditions
Audible noises from the SAI pump area
Failed emissions inspection
Slightly reduced engine performance during warm-up

How to diagnose P2431

A typical diagnostic flow when this code is present.

  1. 1
    Connect an OBD-II scanner, record all stored DTCs, and note any related SAI codes (P0410, P2432, P2440, P2444)
  2. 2
    Inspect all SAI system wiring, connectors, and vacuum lines for corrosion, damage, or disconnection
  3. 3
    With the engine cold, start it and listen for SAI pump operation; confirm the pump activates for approximately 30–90 seconds
  4. 4
    Use a scan tool to activate the SAI pump via bi-directional controls and monitor sensor output voltage — compare against manufacturer specification
  5. 5
    Test the one-way check valve by blowing through it in both directions; it should allow flow in only one direction
  6. 6
    Measure sensor supply voltage (typically 5 V reference), ground, and signal wire resistance at the connector
  7. 7
    Clear codes, perform a cold-start drive cycle, and check whether the fault returns
  8. 8
    If all components test good, check for applicable PCM software updates from the vehicle manufacturer

Related powertrain codes

Frequently asked questions

Can I keep driving with a P2431 code stored?

Short-term driving is generally possible, but the SAI system is not functioning correctly. Prolonged operation without repair accelerates catalyst wear.

Is P2431 always caused by the SAI pump itself?

No. The one-way check valve is statistically the most common culprit and is often overlooked.

What other codes commonly appear alongside P2431?

P0410 (SAI system malfunction), P2432 (sensor circuit low), P2440 (switching valve stuck open), and P2444 (pump stuck on) frequently co-occur.

Does P2431 affect fuel economy significantly?

The SAI system only operates briefly during cold start, so fuel economy impact is minimal.

Disabling P2431 in software

RaceTune can permanently disable P2431 — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

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