What it means
The reductant injection air-pressure sensor A signal jumps or drops out intermittently — connector or harness issue.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The reductant injection air-pressure sensor A monitors the pressure that helps deliver DEF or AdBlue into the exhaust. The control module watches its signal for dropouts or sudden changes; P2041 sets when that signal becomes intermittent rather than remaining stable.
Common causes
Most likely first.
- Intermittent connector or chafed wire
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
How to diagnose it
- Check freeze-frame data and scan-tool live readings for pressure-signal dropouts, and note whether they coincide with engine vibration or changes in operating conditions.
- Inspect sensor A's connector and nearby harness for loose fit, chafing, moisture, corrosion, or wires rubbing against a vibrating component.
- With the system safely accessible, wiggle the connector and harness while watching the live sensor signal to see whether movement reproduces the dropout.
- Check the sensor A circuit connections and continuity while flexing the harness, following the manufacturer's wiring information.
- If the wiring and connector remain sound, test the air-pressure sensor A and its signal against the manufacturer's specification.
Common fixes
- Secure the sensor A connector and repair damaged connector seals or terminals.
- Repair chafed wiring and reroute or secure the harness away from vibrating components.
- Replace the air-pressure sensor A if its signal drops out despite a sound circuit.
Can I keep driving?
You can often drive briefly if the vehicle runs normally, but avoid ignoring a NOx or DEF warning. The emissions system may stop dosing correctly, and an unresolved fault can lead to a no-start countdown or an emissions test failure.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.