OBD-II Diagnostic Trouble Code
P2440 — Secondary Air Injection System Switching Valve Stuck Open Bank 1
The ECM detected airflow from the secondary air injection system into the bank 1 exhaust when the switching (check) valve should have been closed. This is usually seen on the O2 sensor or a secondary air pressure sensor as a lean reading or unexpected pressure with the air pump off. This applies only to gasoline engines with secondary air injection.
Severity 2/5
Less common on commercial trucks
Service soon
Severity
Service soon
Secondary Air Injection System Switching Valve Stuck Open Bank 1
Code
P2440
Category
Powertrain
Subsystem
Emissions
Truck-relevant
Less common
What this means for truckers
P2440 (Secondary Air Injection Stuck Open Bank 1) — gas engine.
Before you replace parts — try this first
P2440 on the Emissions system is most often switching or check valve stuck open from carbon or corrosion — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
The check-engine light is on. Some trucks show a lean condition or rough idle. Because a valve stuck open lets hot exhaust and moisture back into the air system, the air pump may become noisy, seize or fail over time, and melted or burnt hoses are sometimes found.
Common causes
- CommonSwitching or check valve stuck open from carbon or corrosion ($150–$450)
- OccasionalVacuum control solenoid stuck on, holding the valve open ($80–$250)
- OccasionalAir injection pump relay stuck closed so the pump keeps running ($40–$150)
- OccasionalLeaking vacuum lines to a vacuum-operated valve ($30–$120)
How to fix
Remove the switching valve and check whether it seals when off; replace it if it passes air or is carboned
When to use: First step
Check that the air pump relay and control solenoid de-energize when the pump is commanded off
When to use: When the valve itself seals
Inspect the air pump for water or exhaust contamination and replace it if needed
When to use: When the valve has been leaking for some time
Clear the code and run the secondary air monitor on a cold start
When to use: After the repair
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P244A — Diesel Particulate Filter Differential Pressure Too Low
- → P244B — Diesel Particulate Filter Differential Pressure Too High
- → P244C — Exhaust Gas Temperature Too Low Bank 1
- → P244D — Exhaust Gas Temperature Too High Bank 1
- → P245A — EGR Cooler Bypass Control Circuit/Open
Frequently Asked Questions
Can I drive with code P2440?
P2440 is severity 2 — service this week. Not an immediate stop, but ignoring it usually compounds the problem. Most common cause for this code is a worn sensor or minor performance fault that won't strand you today but will get more expensive the longer you wait.
How much does it cost to fix P2440 on a commercial truck?
Total repair cost ranges $30–$450 depending on the root cause. The cheapest fix is usually the first one listed below — Switching or check valve stuck open from carbon or corrosion — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P2440 fail a DOT inspection?
Yes — P2440 is an emissions-related code, and DOT inspectors check emissions compliance. An active emissions code with a check engine light can result in an out-of-service violation under FMCSA Part 393. The truck typically can't be moved until the code is cleared. Repeated emissions violations escalate to CSA scores.
What's the difference between P2440 and related codes?
P2440 is closely related to: P244A (Diesel Particulate Filter Differential Pressure Too Low), P244B (Diesel Particulate Filter Differential Pressure Too High), P244C (Exhaust Gas Temperature Too Low Bank 1), P244D (Exhaust Gas Temperature Too High Bank 1). These codes share the same subsystem (emissions) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P2440 is set without the companions, the issue is more isolated.
How do I prevent P2440 from coming back after a repair?
For P2440 (Secondary Air Injection System Switching Valve Stuck Open Bank 1), prevention centers on the emissions system. Keep up with PM on the EGR system — clean the valve at 200K miles. Use OEM-spec air filters. Don't ignore minor codes; they often escalate into bigger emissions failures.