What it means
Reductant temperature sensor A signal jumps or drops out intermittently — connector or harness fault.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
Reductant temperature sensor A reports DEF temperature for dosing and tank-heating control. P2046 sets when its signal cuts in and out or jumps unexpectedly, pointing to an intermittent sensor circuit rather than a consistently high or low reading.
Common causes
Most likely first.
- Intermittent connector
- 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
- Review freeze-frame data and live sensor A temperature for dropouts or sudden jumps, noting whether they occur with vibration or temperature changes.
- Inspect the sensor A connector and harness for loose fit, corrosion, moisture, chafing, or contact with a vibrating component.
- Watch the live reading while gently moving the connector and harness to see whether movement reproduces the intermittent signal.
- Check circuit continuity and terminal contact while flexing the harness, following the manufacturer's wiring information.
- If the wiring and connector are sound, test reductant temperature sensor A for intermittent failure against the manufacturer's specification.
Common fixes
- Secure the sensor A connector and repair loose, corroded, or damaged terminals.
- Repair chafed wiring and secure the harness away from vibrating components.
- Replace reductant temperature sensor A if its signal remains intermittent with a sound circuit.
Can I keep driving?
If the vehicle runs normally, keep trips short and resolve the fault promptly when a DEF or NOx warning is on. A sensor dropout can disrupt dosing or tank heating, and the warning may progress 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.