P2431: Secondary Air Pressure Sensor Range/Performance (Bank 1)
P2431 means the engine computer reads the secondary air injection pressure sensor on bank 1, but the reading does not make sense compared with outside air pressure. The car is usually drivable, but it will keep the check engine light on and can fail an emissions test until it is fixed.
You can drive, but get it checked soon
The code does not cause limp mode, so the car normally drives as usual. The secondary air system is not working as verified, though, so emissions may be higher after cold starts, and the check engine light can hide other new problems. Have it checked soon, especially if other MAP or lean codes appear.
What it means
The secondary air injection (AIR) system pumps fresh air into the exhaust after a cold start so the catalytic converter warms up faster and emissions stay low. A pressure sensor in that system lets the engine computer see whether the pump is working. To check the sensor, the computer compares it with barometric pressure (the outside air pressure). With the pump off, the two values should match. With the pump running, the rise must stay within set limits. P2431 is set when the sensor signal is present but falls outside those limits, so the signal is readable but wrong. Limits differ by manufacturer. For example, GM uses a gap of more than 10 kPa with the pump off or 50 kPa with it on for over 30 seconds on the 3.8L V6 (2005-2006), and Volkswagen allows up to 60 hPa deviation on the 2014 Beetle 1.8 TSI. Plain electrical faults in the sensor circuit are set under P2432 and P2433 instead.
Likely causes
- Pressure sensor drifted or reacts too slowlyVery likely
An aging sensor can give readings that no longer match real pressure, so the comparison with barometric pressure fails.
- Wrong barometric reference, e.g. damaged MAP sensor wiringPossible
The test relies on a correct barometric value, and GM bulletin PIP4409E links P2431 on Colorado, Canyon and H3 to broken MAP sensor wires.
- Restricted or leaking air duct around the sensor portPossible
A blocked or leaking passage keeps the sensor from seeing the true pressure when the pump is off or running.
What you may notice
- Check engine light, often only after cold starts
- Secondary air monitor not completed, which can block an emissions inspection
- Possibly further MAP or lean codes if the reference is wrong
What to check, cheapest first
- 1Read all stored codes and freeze frame data. Look for MAP, lean, or other secondary air codes (P2430, P2432, P2433, P2436, P0411) that point to the real cause. · you can do it
- 2Inspect the wiring and connector at the MAP sensor and the secondary air pressure sensor for breaks, chafing, corrosion, or loose pins. · you can do it
- 3Check the air hoses and ducts around the sensor port for cracks, loose connections, blockage, or leaks. · you can do it
- 4With the key on and the pump off, compare the sensor reading with the barometric pressure on a scan tool. They should agree. · mechanic
- 5Command the air pump on and watch the pressure rise to see whether the sensor responds correctly and quickly enough. · mechanic
- 6Replace the pressure sensor if the readings are off and the wiring and ducts are good, then clear the code and run the drive cycle so the monitor can complete. · mechanic
Related codes
Frequently asked questions
Can I keep driving with P2431?+
Usually yes for a short time, since limp mode is not expected. Emissions may be higher after cold starts, so get it checked soon.
Can a loose gas cap cause P2431?+
No. A gas cap affects fuel vapor (EVAP) codes, not the secondary air pressure sensor. Look at the sensor, its wiring, the MAP sensor, and the air ducts instead.
Will P2431 pass an emissions test?+
Probably not. The code is emissions related and turns on the check engine light, and the secondary air monitor may not be complete. Fix it and finish the drive cycle before testing.
Can I fix it myself?+
Often yes. Repair difficulty is medium, and the estimated time is about 0.5 to 2.5 hours. Checking wiring and hoses is the cheapest place to start.
Written with the help of AI from the public OBDex definition (CC0). Each make may use the code differently. Updated: 2026-11-10