Mercedes Repair Questions? Ask a Mechanic for Answers ASAP
Hi, a code 22 is a heater circuit code. You need to make sure you have 12V to the sensor heater. If you have the voltage at the sensor you need to disconnect the connector at the N16 module and check from pin 1 to pin 20 in the connector with your ammeter. You should get between 0.5 - 1.7 amp draw on the heater circuit. If you don't get your readings you either have an open circuit on the ground side of the sensor or a fault with the new sensor.
Click on the attachment below.
Make sure pin 20 is the heater wire. My diagrams are not consistent.
You're welcome, Bill.
You should check it while it is connected. Use jumper leads if necessary.
It probably doesn't matter but I would test it with the key on engine running.
Hi Bill, are you sure you are testing the correct wire? What your test is telling me is that the heater is open or there is an open or poor connection in the harness. You can unplug the sensor and run a separate power and ground to the sensor with an ammeter inline to test just the sensor itself. Also make sure that the fuse in your ammeter is good.
It should switch right when you get back to idle but may stop switching if it idles long enough with the heater inoperative.
I'm in Florida. I'm usually around until about 8 PM EST.
The flickering dash is usually caused by poor fuse connections or a bad capacitor on the instrument cluster circuit board. You should first replace the fuses for the instrument cluster. Fuse 1, 5 and 9. The spec on the heater is 0.5 - 1.7 amps. It sounds like you have a defective sensor.
I doubt you are getting bad sensors. How did you retrieve the code 22?
you never got back with me and the case closed..any thoughts? thanks
I agree with you about the amperage but it doesn't seem right that 2 Bosch sensors would be defective. What I meant about the code is which socket in the 38 pin connector are you plugging into in order to get the code 22.
ahh, yes, PIN#3
Pin 3 is the power supply and pin 1 is ground. You should have a third lead to probe the other pins in the 38 pin connector to pull codes from the various modules.
We are using a snap modus scanner with a clip for the ground. the scanner powers itself and pin #3 allows us to read the code 22 on the snapon screen. let me know, please
That does not sound correct. Pin 3 is just a 12V feed. Are you plugging into the 38 pin connector under the hood?