A great question I was recently asked. The parts store diagnosed my check engine light, why do I need to pay for a shop to do it? See a previous post, https://posts.gle/Mds3mM. But here are some additional thoughts. Some “Diagnostic Trouble Codes” or DTC’s are very straightforward. They tell you exactly what’s wrong. Like a P0128, thermostat not working. Or a P0420 Catalytic Converter not efficient/not doing its job.
Other codes are not so straightforward. 2011 Jeep Grand Cherokee with an Airbag warning light. DTC of, U11B0 Lost Communication With Right Side Satellite Sensor 4. I know what you’re thinking. Just replace the sensor!! Well, here is the list of “Probable Causes” directly from the manufacturer.
(r140) Right Side Impact Pressure Sensor Signal Circuit Open
(r140) Right Side Impact Pressure Sensor Signal Circuit Shorted To Ground
(r140) Right Side Impact Pressure Sensor Signal Circuit Shorted To Voltage(r140)
(r160) Right Side Impact Pressure Sensor Circuits Shorted Together
(r160) Right Side Impact Pressure Sensor Ground Circuit Open Occupant Restraint Controller (orc)
So according to the manufacture this code has nothing to do with the sensor. It is all circuit related. Meaning the connections or wires between the sensor and the computer. I used this code as an example because we just fixed it. The connector inside the door jamb was disconnected.
So, what’s my point? Well, there are several codes that you can fix by replacing parts. But please seek advice from your trusted shop before “Throwing” parts at your car. You will be better informed and less stressed. By knowing the part, you just installed will turn off the warning light. By the way, if you do replace a part based on a code. Remember to have the codes cleared. The warning light will not shut off until all the monitors are run and completed. Which could take a couple days based on your driving habits.