P2433 – Secondary air injection (AIR) system, air flow/pressure sensor, bank 1 – circuit high

Randy Worner

By Randy Worner (Contact Me)
Last Updated 2016-08-23
ASE Master Tech

Trouble CodeFault LocationProbable Cause
P2433 Secondary air injection (AIR) system, air flow/pressure sensor, bank 1 - circuit high Wiring short to positive, air flow/pressure sensor

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What Does Code P2433 Mean?

Secondary AIR

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 kickstart 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 P2433 will set when the voltage being returned by the sensor is greater than 4.8 volts for usually 2 seconds but varies by mfg so please consult your vehicle specifications.

What are the common causes of code P2433?

  • Plugged or restricted passage to A.I.R. System Pressure Sensor – most common-water drain from the exhaust (heat resistant silicone hose required)
  • High resistance in connections to either A.I.R. System Pressure Sensor or BARO Sensor – next most likely possibility.
  • Failed A.I.R. System Pressure Sensor or BARO Sensor – possible
  • Failed PCM – unlikely

What are the symptoms of code P2433?

  • Malfunction Indicator Light “ON”
  • Possibly Reduced Engine Power
  • Possible noises from the A.I.R. pump, depending upon the failure and how long failure has been occurring

How do you troubleshoot code P2433?

First, take a look and see if there are any technical service bulletins (TSB) for your particular vehicle. There may be an update, or known fix put out by the manufacturer that can save you from wasting time and money.

Next, see if there are any other diagnostic fault codes. Diagnose current faults first, in the order in which they are stored. Misdiagnosis occurs when this code is diagnosed when it is a stored code, especially while other codes are active. Also, check for active P0651 and P0106 fault codes. If these codes are present, diagnose them before attempting to diagnose the P2433.

If the P2433 is the only active fault code present, and there are no updates/TSBs for your particular vehicle, then the next step is to locate A.I.R. System Pressure Sensor on your particular vehicle. Once located, visually inspect the connectors and wiring. Look for chafing, rubbing, bare wires, burn spots or melted plastic. Pull the connectors apart and carefully inspect the terminals (the metal parts) inside the connectors. See if they look corroded, burnt or possibly green in color versus the normal metal color you are probably used to seeing. You can get some Electrical Contact cleaner at any parts store if cleaning of the terminals is needed and a light plastic bristle brush to clean them with. Afterwards let them air dry, get some dielectric grease (same stuff they use for light bulb sockets and spark plug wires) and put some where the terminals come into contact.

If you have a scan tool, clear the diagnostic trouble codes from memory, and see if this code returns. If it does not, then the connections were most likely your problem.

If the P2433 code does return, we will need to test the sensor and its associated circuits. Typically, there are 3 wires at the A.I.R. System Pressure Sensor.

Disconnect the harness going to the A.I.R. System Pressure Sensor. The sensor is usually part of the Secondary Air Check Valve. For this code, the easiest thing to do is take a fused jumper wire (that’s a jumper wire with a fuse in line; it protects the circuit you are testing) and connect the SIG RTN (the sensor’s ground) wire to the A.I.R. System Pressure Sensor Signal input wire. With the scan tool hooked up, monitor the A.I.R. System Pressure Sensor volts. It should now read close to zero volts. If a scan tool is not available that has a data stream, then see if code P2432 A.I.R. System Pressure Sensor Circuit Low Input is now set after 15 seconds. If either of these have occurred, then the wiring and PCM are good. The most likely problem is the sensor itself. Don’t forget the obvious. Insure the passage from the sensor to the exhaust is intact; complete, no holes, no blockage.

If all tests have passed so far, and you continue to get a P2433 code, this would most likely indicate a failed A.I.R. System Pressure Sensor, although a failed PCM could not be ruled out until the sensor had been replaced. If unsure, seek assistance from a trained automotive diagnostician. And remember, PCMs must be programmed, or calibrated to the vehicle in order to be installed correctly.

Codes Related to P2433

P2430, P2431 & P2432 Secondary air injection (AIR) system pressure sensor faults – P2430 may set along with P2433 as it is a generic failure of the Secondary AIR Pressure Sensor. P2431 and P2432 are unlikely to set along with the P2433, as their requirements to set are entirely different.

P0106 & P0651P0106 is for the BARO Pressure Sensor and P0651 is for the 5 V Reference Voltage fault. If either of these 2 are present, you diagnose them first before diagnosing the P2433 – can and will affect the diagnosis of the P2433.

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