Electrical connections of NOx sensor. 2EAE

2EAE message of nitrogen oxide sensor 1 missing (timeout)


Few times per second MSD80 sends command or data request to NOx sensor. One hundred times per second NOx sensor “answers” to MSD80: execute required commands or sends measured data.

If there are interruptions in communication, error code 2EAE is recorded immediately.

If this error message is recorded together with another error messages relating NOx sensor (typically: errors about Lambda binary and Lambda linear), NOx sensor is damaged and has to be replaced, but if there are no other error messages relating NOx sensor stored and/or replacement of NOx sensor doesn’t help – several specific check-up procedures has to be proceeded.


There are three main groups of reasons, why this error message can appear:

  1. Defects of NOx sensor itself;
  2. Problems with power supply of NOx sensor;
  3. Problems with CAN data channel communication.

In very rare cases MSD80 can be cause of this problem (CAN driver or it’s ESD protection devices are damaged).

NOx sensor connection description

  • [1] Power supply; +12V
  • [2] GND; ground
  • [3] CANL; CAN, Low
  • [4] CANH; CAN, High
  • [5] NC; not connected


How to check power supply

Required tool: multimeter or (even better) – test bulb (12V; 1 .. 20W).

Test method:

  1. Turn on ignition;
  2. Connect multimeter (range: 20VDC) or test bulb between Pin [1] and Pin [2].

Multimeter readings should be equal car’s battery voltage (10 .. 15V). Test bulb should light up.


Additional test (if multimeter is used): measure resistance between Pin [2] and car’s chassis (for example: exhaust pipe or NOx sensor’s fixing bolt). Resistance should be close to zero (less than few Ohms). If resistance is increased – check ground wiring and connector.

Also connector should be inspected. If mechanical damage, oxidation of contacts, damage of wireset isolation is noticed, connector should be replaced (ordering codes – at the end of entry).

Note: both tests (using multimeter and test bulb, even if they show presence of power supply) doesn’t guarantee proper ability of performance of NOx sensor due to damaged connector (increased transition resistance of contacts due oxidation). Connector should be tested very carefully also visually.


If power supply problem is not confirmed, proceed further inspection of problem.

Specific damage of OEM NOx sensor (short circuit: damage of power stage snubber diode or short circuit: damage of heating element of NOx sensor) can be the cause of this issue.

Check fuse F06. If fuse is blown, check old NOx sensor for short circuit before replacing the fuse:

  1. measure resistance between Pin [1] and Pin [2]. If resistance is close to zero (few Ohms)  the sensor is damaged;
  2. measure resistance between Pin [1] and sensor’s body and/or between Pin [1] and sensor’s housing. If resistance is close to zero (few Ohms) – the sensor is damaged.


Next two pictures show power wireset connection. As shown in schematics, several units are connected to the same power line:

  1. Radiator shutter flap (one or two modules)
  2. Secondary air pump (relay)
  3. Exhaust flap
  4. E-box fan
  5. AUC sensor
  6. Brake air flaps (left and right)
  7. Fuel tank leakage module (USA)
  8. Secondary film air mas meter (USA)
  9. NOx sensor


Some of these units are optional (for example – brake flaps), some of them can have different configuration (for example: engine cooling flaps can be at one or two separate modules, controlled by electro-magnet, and/or additional controller), some of these units are dedicated for specific markets (for example: fuel leakage module – for USA market). Schematics of yours car can differ from example – please check details using ISTA D or WDS.


Causes of blown fuse (F06 on example) can be overload or short circuit to ground.

If 2EAE re-appears after NOx sensor replacement (F06 is blown repeatedly) – check wireset and all modules connected to this power wire.


If test of power supply confirms presence of necessary voltage, connection of CAN should be performed.


  1. Disconnect battery;
  2. Disconnect NOx sensor and, using multimeter,  using multimeter  (connector/wireset) between Pin [3] and Pin [4]. Proper value –  110 .. 130 Ohms;
  3. Check resistance between Pin [3] and chassis; between Pin [4] and chassis (connector/wireset). Proper value (on 200 Ohm range) – over limit;
  4. Check internal resistance of NOx sensor (NOx sensor’s connector): between Pin [3] and Pin [4]. Proper value –  110 .. 130 Ohms for OEM NOx sensor;*
  5. Check of internal leakage of NOx sensor (NOx sensor’s connector): measure resistance between Pin [3] and Pin [2]; between Pin [4] and Pind [2]. Proper value (on 200 Ohm range) – over limit;
  6. Connect NOx sensor. Measure (wireset) resistance between Pin [3] and Pin [4]. Resistance should be 55 .. 65 Ohms if OEM NOx sensor connected.*

*for corresponding NOXEM values please contact Bimmerprofs

If test [2] shows zero resistance – there is a short circuit in wireset (high probability) or MSD80 CAN driver is damaged (low probability). If resistance is significantly higher that it should be – check wireset and connector(s). If wireset and all connectors (including MSD80 connector) are in working condition – CAN driver (chipset) of MSD80 is damaged (low probability): repair or replace MSD80.

If test [3] shows low resistance – check wireset (high probability), if wireset is not damaged – MSD80 CAN drive’s ESD protection devices and/or CAN driver are damaged (low probability) – repair or replace MSD80.

If value, measured in test [4] doe’s not correspond – NOx sensor is damaged. Replace sensor.

If value, measured in test [5] is low, sensor is damaged (it’s ESD protection devices and/or CAN driver).

If test [6] still shows resistance around 120 Ohms – NOx sensor’s (wireset side) connector is damaged. Replace connector.


Ordering codes for NOx sensor’s connector

Connector NCON 1.2; p/n 1-1718806-1

Contacts (5 pcs); p/n 1418844-1

Seal plug (5 pcs); p/n 964972-1


Warning: due to high over voltage spikes from ignition coil’s wireset (problem described here) some vehicles have risque of MSD80 and/or peripheral (NOx sensor; exhaust temperature sensor, etc) damages. Some inexplicable cases when NOx sensors are repeatedly damaged (after few hundreds or thousands km) are described in Internet. The proper solution of this problem – installation of snubbers (with snubbers installed over-voltage spikes are totally suppressed), also additional wireset isolation (using tape or PVC tube) can be performed.