Number P2431: AIR System Air Flow/Pressure Sensor Circuit Range/Performance (Bank 1)
P2431 flags a bank 1 secondary air pressure signal that can be read but makes no sense. The usual check compares the sensor with barometric pressure: with the pump off both should agree, with the pump running the rise must stay within limits. GM sets the code on the 3.8L V6 (2005–2006) when the gap
Can you drive with P2431?
Severity: Plan the repair. Yes — this is an emissions-system fault. The car will generally drive normally, but it will fail an emissions inspection with the light on.
If you ignore it: Fuel economy and emissions creep up, and some faults in this family (rich/lean running) stress the catalyst over time.
This is the #150 most common code in our top-150 library, in the electrical, charging & network family (Powertrain system). Severity is Number Nest's editorial triage — if the light is flashing or the car feels unsafe, stop driving it whatever any page says.
What P2431 means
P2431 flags a bank 1 secondary air pressure signal that can be read but makes no sense. The usual check compares the sensor with barometric pressure: with the pump off both should agree, with the pump running the rise must stay within limits. GM sets the code on the 3.8L V6 (2005–2006) when the gap exceeds 10 kPa with the pump off or 50 kPa with it on for over 30 s, Type B; the 2018 table works with 15 kPa and 50 kPa. Volkswagen's 2014 Beetle 1.8 TSI allows a deviation of up to 60 hPa from ambient pressure, the Golf CBFA engine only 25 hPa. GM bulletin PIP4409E links P2431 on Colorado, Canyon and H3 to broken MAP sensor wires, because the comparison relies on a correct baro value. Pure circuit faults go under P2432/P2433.
Systems involved: air system flow sensor b1, sai wiring.
Causes, ranked by likelihood
| # | Cause | Likelihood |
|---|---|---|
| 1 | Pressure sensor drifted or reacts too slowly | most likely |
| 2 | Wrong barometric reference, e.g. damaged MAP sensor wiring | possible |
| 3 | Restricted or leaking air duct around the sensor port | possible |
Check them in order — the list is ranked so the likely, cheaper causes come before the expensive part.
Symptoms you may notice
- Check engine lamp, often only after cold starts
- Secondary air monitor not completed
- Possibly further MAP or lean codes if the reference is wrong
Misdiagnosis traps
- Replacing the part named by the code title without testing. The code reports a failed self-test; the cause list above is ranked so the likely, cheap causes are checked before the expensive part is condemned.
- Clearing the code and declaring victory when the light stays off for a day — the monitor that sets this code runs only under specific driving conditions.
(General diagnostic guidance for this code family — no code-specific trap is published for this code.)
How a good shop confirms it
- Confirm the code and record any companion codes — companions narrow the system fast.
- Inspect the affected components and their wiring/connectors for damage, corrosion and looseness.
- Test the top-ranked cause with live data or a multimeter before replacing anything.
(Standard diagnostic path for this family, labeled as general guidance.)
Repair options & costs
| Repair | Shop total (parts + labor) | DIY (parts only) | Difficulty |
|---|
No single repair is costed for this code — the fix follows the diagnosis. The Repair Cost Estimator prices 28 common repairs once you know which one this is.
OBDex repair data for this code rates the job difficulty medium with a typical labor time in the 0.5–2.5 hour range and DIY possible: yes.
Frequently asked questions
How much does it cost to fix P2431?
There is no single fix — the code names a system, and the cost follows whichever cause on the ranked list proves out. The Repair Cost Estimator prices the common repairs in that system; diagnosis (often $100–$180, frequently credited) comes first.
Can I drive with P2431?
See the can-you-drive verdict above — it is based on the system involved and the cascading-damage risk, and it is our editorial triage, not a manufacturer instruction. If the light is flashing or the car feels unsafe, stop driving it regardless of any code.
Will P2431 clear itself?
If the fault was a one-off (a loose cap, a cold-start glitch), the light can go out after several clean trips and the code ages into history. A fault that is still present re-sets the code as soon as the car runs that self-test again — monitors run under specific conditions, which is why "it hasn't come back in two days" is not proof of a fix.
Will my car fail inspection with P2431?
In states with OBD-based emissions inspection, yes — an illuminated check-engine light or an incomplete readiness monitor fails the test regardless of what the tailpipe would show. C-codes (ABS) fall under safety inspection instead in states that have one.
What should I check first for P2431?
The first item on the ranked-causes list above — it is ranked likelihood-first for exactly this reason — plus the free checks: recent work in the area (connectors left loose are a classic), fluid levels, and the battery and grounds on electrical codes.
Where this data comes from
Code facts, causes and symptoms come from OBDex — an open dataset of independently authored descriptions of the standardized generic OBD-II codes (CC0 1.0, public domain; github.com/foerbsnavi/OBDex). The SAE J2012 document itself is copyrighted and is not reproduced here. Cost ranges are Number Nest's own US planning model: national parts and labor ranges cross-checked against the CarMD Vehicle Health Index 2026 published averages, with labor adjustable by the BLS OEWS May 2025 state wage index for auto technicians (occupation 49-3023) — a wage index, not a surveyed shop rate. Severity and can-you-drive notes are our editorial triage, not a manufacturer instruction.