This week we were working on a Mercedes-Benz E-Class that had deployed airbags.
The owner had replaced the seat belt retractor because of a minor accident, and the seat belts had locked up. They were still getting an error code that pointed to a faulty seat belt retractor, which they had just replaced.
When an airbag deploys, you typically will get a code such as:
- The resistance value in the ignition circuit containing components ( right, left, front, rear) ignition squib is too high.
The initial code, in this case, was: "9202. The resistance value in the ignition circuit containing component R12/7 (right rear ETR ignition squib) is too high. Code Current and stored. "
The problem here is that even after replacing the retractor, it was still showing a fault code, and of course, you are not able to clear the SRS warning light.
Upon further diagnostics, we found that this was a different code. The fault code for the right rear seat belt retractor had changed.
In this case, the fault code had changed to:
"9203 - The resistance value in the ignition circuit containing component R12/7 (Right rear ETR ignition squib) is too low. "
As you can see here, the airbag fault code changed from resistance too high to resistance too low. The reason is that the new "used" retractor had wasn't meant for this car. It also had the wrong part number.
The resistance in the ignitor was not matching what the car was looking for, and thus, it was throwing a fault code in the airbag module.
Replacing the retractor with the correct unit changed the code from current to stored. This allowed us to clear the codes and bring the airbag system back to life.
Resistance too low code can also because the wire harness connector is not locked in the airbag module. In the picture above, you can see the green connector. The orange tab needs to be in the lock position.
The troubleshooting tips in this article are for information only. Replacing airbag units with used airbags is illegal in some states and countries. Improper repair of airbag components is generally unlawful.