Fix P2432: Mechanic’s solutions that WORKED

The P2432: Secondary Air Injection System Air Flow/Pressure Sensor Circuit Low Bank 1 indicates a problem with the air flow/pressure sensor circuit in the secondary air injection system, particularly on Bank 1. This system introduces fresh air into the exhaust stream to reduce emissions during cold engine starts. When the sensor detects a voltage lower than expected, it triggers this fault code.

P2432 quick overview

Meaning	P2432: Secondary Air Injection System Air Flow/Pressure Sensor Circuit Low Bank 1
Is it serious?	This code is generally not very serious, but it can affect emissions and overall engine performance. It’s advisable to address it to prevent potential issues.
Possible causes	– Faulty air flow/pressure sensor – Wiring or connector problems in the sensor circuit – Issues with the secondary air injection system components
How to diagnose?	Check Sensor Location: Locate the air flow/pressure sensor in the secondary air injection system. Inspect Wiring and Connectors: Examine the sensor’s wiring and connectors for damage, loose connections, or corrosion. Test Sensor: Test the air flow/pressure sensor to ensure it’s functioning correctly. Check Secondary Air Injection System: Inspect the components of the secondary air injection system, including the pump and valves, for any faults. Clear Diagnostic Codes: After any necessary repairs, use a diagnostic tool to clear the fault code and monitor if it returns.

How to fix P2432 – learn from mechanics

I looked into P2432 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Saturn

Vehicle Information: 2007 Saturn Ion-2 2.2L

Issue + Repair History:

• Check Engine Light on with code P2432 (Air Injection System Pressure Sensor circuit low voltage).
• No other symptoms reported.
• Previous attempts to diagnose included checking the electric air injection pump relay and fuse, the electric valve and relay, and the Baro/MAP Sensor.

Other OBD2 Codes + Test Results:

• P2432 – Air Injection System Pressure Sensor circuit low voltage.

Suggestions to Fix Issue:

• Check for short to voltage in the 5-volt reference or the signal.
• Inspect the air solenoid valve for any possible faults.
• Consider circuit testing to rule out electrical issues.

Final Fix:

• The issue was resolved by replacing the electric air solenoid valve.

Case #2: Isuzu

Vehicle Information: 2008 Isuzu Ascender S 4.2L

Issue + Repair History:

• Check Engine Light on with codes P0411 (Secondary air, incorrect flow), P2432 (SA pressure sensor circuit low voltage), and P2440 (SA shut off valve stuck open).
• Previous repair history includes replacing the solenoid valve with a pressure sensor.

Suggestions to Fix Issue:

• Check for the presence of check valves on the manifolds, as a leaking check valve can cause a P0411 code.
• Consider the possibility of a faulty AIR valve as they are known to go bad frequently.
• Inspect the pressure sensor in the valve, even if it’s new, as it may still be faulty.
• Check the voltage to the solenoid, which should be 5V when unplugged.

Final Fix:

• The issue was resolved by identifying a faulty secondary air valve, despite it being a new replacement. Replacing the faulty valve fixed the problem. Additionally, the voltage to the solenoid was found to be low, indicating another issue that may need further investigation.

Case #3: Volkswagen

Vehicle Information: 2012 Volkswagen Passat SE 2.5L

Issue + Repair History:

• Check engine light on with codes P2433 (short to negative for secondary air pressure sensor) and P2432 (short to positive for secondary air pressure sensor).
• Replaced the secondary air sensor as per manufacturer instructions.
• Code P2433 (short to negative) remains uncleared.

Test Results:

• 12v pin 1 to battery +: Has 12v
• 5v pin 3 to battery +: Has 5v
• 1.5 ohms pin 4 to pin t60/55 at ECM: Has 1.5 ohms

Suggestions to Fix Issue:

• Check the voltage from the sensor at the PCM pin, which should be less than 4.5V. Anything higher may indicate a broken wire or high resistance.
• Investigate the possibility of an updated sensor and hose combo, as there is a bulletin on these sensors that may entail installing a new pipe with a pigtail and pressure sensor.
• Look for any leaks in the system as they can also trigger these codes.
• Consider creating a jumper harness to the ECM to test if the code clears, and if it does, make it permanent.

Summary: The issue with the check engine light has not recurred, and the customer has not returned, possibly due to traveling out of state. The specific cause of the persistent P2433 code was not resolved in the available information.

Case #4: Pontiac

Vehicle Information:

• 2006 Pontiac Grand Prix 3.8L

Issue: The vehicle shuts off under specific conditions: wide-open throttle (WOT) and spinning the engine until the tachometer reaches 5500 rpm. When this happens, the engine completely shuts down, requiring the driver to put the car in neutral and restart the engine. This issue is repeatable and not random.

Diagnostic Steps:

• Checked crank sensor pattern and cam position sensor pattern using a lab scope (Pico), and both waveforms appear good.
• Monitored four channels: CKP (Crankshaft Position Sensor), CMP (Camshaft Position Sensor), current probe at ignition module power, and current probe on the number 1 fuel injector.
• Voltage to the ignition module first goes away, followed by the fuel injectors shutting down. The fuel injectors do not come back until the engine is restarted, but voltage returns to the ignition module.
• Observed that when the shutdown occurs, the PCM (Powertrain Control Module) ground to the power control relay is lost first, and then the computer attempts to ground it 3.5ms later for 300us. It repeats this process 8.4ms later, and this time it stays grounded.

Questions and Theories:

• Is the computer shutting down the relay to protect itself?
• Could the computer be doing this randomly?
• Could it be related to shifting, as the problem occurs under specific RPM and throttle conditions?
• Is there a possibility of a corrupt ECM (Engine Control Module) program?

Summary: The issue of the engine shutting off at 5500 rpm under WOT conditions remains unresolved. The exact cause of this problem, whether it’s a safety feature, a malfunction, or a programming issue, is not definitively determined based on the available information. Further diagnostic steps or consultation with experts in engine control systems may be necessary to pinpoint and rectify the issue.

Case #5: Toyota

Vehicle Information:

• Make: Toyota
• Model: Camry
• Year: 2010
• Engine: 2.5L 4-cylinder

Issue: The owner of a 2010 Toyota Camry brought the vehicle to the shop with a check engine light illuminated. Upon scanning the vehicle’s onboard diagnostics, the following trouble code was retrieved:

Trouble Code: P2432 – Secondary Air Injection System Pressure Sensor Circuit High Voltage

Mechanic included diagnostic steps:

1. Visual Inspection: The first step was a visual inspection of the secondary air injection system components, including hoses, valves, and the pressure sensor. No visible damage or loose connections were found.
2. Check Wiring and Connectors: The technician then checked the wiring harness and connectors related to the secondary air injection system and pressure sensor. All connections were secure and free from corrosion.
3. Testing the Pressure Sensor: To verify the functionality of the pressure sensor, a multimeter was used to measure the voltage at the sensor connector. The voltage reading was found to be within the specified range.
4. Checking Air Pump Operation: The air pump responsible for the secondary air injection system was tested to ensure it was functioning correctly. It was found to be operational, supplying air to the exhaust system as intended.
5. Clearing the Code: The technician cleared the trouble code P2432 from the vehicle’s computer to see if it would return after further testing.
6. Road Test: The Camry was taken for a road test to monitor the secondary air injection system’s performance. During the test, the technician observed that the secondary air injection system was operating as expected, and there were no noticeable issues with the vehicle’s drivability.
7. Re-Scan: After the road test, the vehicle was rescanned for trouble codes. No codes were present, including P2432.

Conclusion: Based on the visual inspection, testing of components, and road test results, it was determined that there were no actual issues with the secondary air injection system or its pressure sensor. The initial P2432 trouble code was likely triggered by a temporary glitch or electrical anomaly.

Advice	Diagnostic Step Description
Check for Loose or Damaged Connections	Inspect wiring harness and connectors for any issues.
Verify the Secondary Air Injection System’s Operation	Test the air pump and other components for proper function.
Clear the Trouble Code and Monitor for Recurrence	Reset the code and observe if it returns during operation.
Perform a Visual Inspection of System Components	Examine hoses, valves, and sensors for visible damage.
Check the Voltage at the Pressure Sensor Connector	Use a multimeter to measure voltage within specified range.