P11D7 Possible Causes
- Faulty nitrogen oxide (NOx) sensor
- Nitrogen oxide (NOx) sensor harness is open or shorted
- Poor electrical connection in the nitrogen oxide (NOx) sensor circuit
How to Fix Code P11D7?
Start by checking the “possible causes” listed above. Visually inspect the corresponding cable harness and connectors. Look for damaged components and check for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
- Check Engine Light On (or Service Engine Soon Warning Light)
P11D7 Meaning
The reduction system uses two nitrogen oxide (NOx) sensors to monitor the amount of NOx in the engine exhaust gases. The first sensor is located at the turbocharger outlet and monitors the engine’s NOx level. The second NOx sensor is located between the selective catalytic reduction (SCR) and the diesel particulate filter (DPF) and monitors NOx levels downstream of the SCR. The second NOx sensor also provides the Engine Control Module (ECM) with information about the exhaust oxygen level during DPF regeneration.
Each NOx sensor contains a sensing cell, a pumping cell, and a heater. An exhaust gas sample passes through a diffusion gap between the sensing cell and the pumping cell. The NOx sensor maintains a constant reference voltage across the sensing cell. An electronic circuit inside the sensor controls the pump current through the pumping cell to maintain a constant voltage in the sensing cell. The amount of current required to maintain the reference voltage in the sensing cell is proportional to the NOx concentration in the exhaust.
The ECM varies the amount of diesel exhaust fluid (DEF) or reductant added by varying the duty cycle of the reductant injector in response to changes in engine exhaust NOx levels.
Intelligent NOx sensors consist of two components, the NOx module and the NOx sensor element, which are serviced as a unit. A circuit or performance condition with a NOx sensor is detected by the NOx sensor module. The intelligent NOx sensor module communicates the condition to the ECM via the serial data line. The ECM sets a DTC when a serial data message is received from the NOx sensor module.