How to use the NOx sensor emulator NOXEM 402

  1. Replace the existing NOx sensor to NOx emulator
  2. Clear errors and proceed desulfation session (for ISTA D/+ only)
  3. Perform service procedure ‘’Reset adaptation values and versions (encoding)’’ using ISTA D/+ or clear all adaptations using INPA for F series (recommended). This procedure will:
    • clear adaptations of NOx sensor;
    • clear status and profile of NOx catalytic converter (INPA only);
    • clear all old adaptations of the engine.
  4. Create new adaptations: proceed re-adapt of the engine
  5. Clear errors and clear NOx sensor’s adaptations repeatedly if necessary
  6. Check if the Stratified charge is renewed



  • After installing and coding the procedure of NOXEM, the positive effect is not reached immediately – it takes some time. First driving sessions after replacing the sensor maybe with increased engine unevenness – the engine will measure the performance of each cylinder in different driving conditions: it will restore correct adaptations.
  • Some specific adaptations are performed only in conditions of even load and RPM. That’s why it is so important (after installing and coding of NOXEM), in first driving sessions (also after creating the initial adaptations, as described below) to allow the engine warm-up in idle, drive as smooth as possible and with longer driving sessions. In such a way, the engine will reach even performance as quickly as possible.
  • Immediate symptom, that the installation of NOXEM was successful: after new adaptations are completed, the engine (again) runs in a Stratified charge when driving evenly – fuel consumption is decreasing.
  • In the initial stage, after installing NOXEM the engine will intensively create adaptations for exact driving conditions: most often it will switch to Homogeneous mode. It is normal and very typical for this engine – adaptations (also smoothness measurements of cylinders) are performed for each mode – Homogeneous, Homogeneous lean, Stratified charge – separately.
  • If in any of injection modes the engine runs with increased vibration (it feels like a diesel engine) – allow the engine run in this mode for some time (5 .. 10 min). MSD87 will identify unevenness and will immediately start to eliminate it.



Replacement of NOx sensor

  1. Take off the plastic shields in the middle area of passenger side floor;
  2. Disconnect the NOx sensor data cable;
  3. Unscrew two M6 screws;
  4. Unscrew the probe of NOx sensor, using 22 mm tool;
  5. Screw-in the probe of NOx emulator;
  6. Fix NOx emulator, using two M6 screws;
  7. Draw the NOx emulator probe, using 22 mm tool with force 10 .. 30 Nm;
  8. Connect the NOx emulator data cable;
  9. Secure the plastic shields (protection cover) back in place.

Attention! Do not use aerosol type spray (brake cleaner, WD40 and similar) during replacement of the sensor! The fume of these sprays can damage the sensor! Remove the protective cap from the sensor directly before installation. If the spray is previously used, dry the surface using compressed air for several minutes.

Additional information


Encoding procedures using ISTA D/+

1. Start a new session in ISTA D/+, perform the identification of the vehicle and a test;

2. Clear all errors;

3. Perform desulfation session of NOx catalytic converter as described here;

4. Clear adaptations and proceed re-adaptation of the engine as described here;

5. Check if a Stratified charge is renewed as described here.



Encoding procedures using INPA (recommended)

1. Clear old adaptations and perform re-adaptation of the engine as described here;

2. Check if a Stratified charge is renewed as described here.


Note. If ”12C 401: Plausibility, signal activity too low” error was stored, follow this link.