“To err is human; to forgive, divine” is a phrase that you may have heard at one time or another. In the automotive business, however, an error could be very costly and just may not be forgiven by the vehicle or shop owner. In this article, I will provide you with real-world shop mistakes that I and others have made. Some are costly in time or parts that both affect the shop’s bottom line; and, in other cases, costly in terms of one’s reputation.
Our first tale
One of the problems that we encountered in our shop recently was on a 2008 Honda Accord with 125,000 miles that had come back after a timing belt and tune up were performed. The owner returned to our shop because of an illuminated check engine light that resulted from an engine misfire. After the tech connected the Honda factory scan tool, he retrieved the misfire DTCs (Figure 1) along with a P0339 Crank Sensor DTC. It’s never good when a customer returns with any problem after a repair has been recently performed on their vehicle. The return of the MIL light is the telltale sign that the vehicle’s computer system sees something wrong and is going to alert the driver. There is no way, at least with drivability issues, that you can hide from doing it right. So, we had to handle the vehicle owner very carefully and be honest with her on what the problem was. We explained what went wrong and caused the MIL light to illuminate and what we were going to do to make it right.
Before we dive too deep into this misfire and crank sensor problem, a good suggestion would be to read up and understand the DTC description before moving forward. Since this looked like a simple problem that may be the result of possible defective ignition part, the tech performed the usual diagnostic routine. Well, in this case it was a lesson that was going to be learned the hard way. Since many technicians would start testing the ignition and fuel system as their first part of the diagnosis, they would not find the root cause of the problem on this Accord. The next logical step that the technician would most likely perform is checking the crank sensor and possibly replacing it, without repairing the problem. Some of the first steps to perform are having a vehicle owner Q&A, visual inspection, system scan and a (Figure 2) TSB check. In this case, there was a TSB for this Honda that describes the DTCs and lists the potential problems, such as a weak battery that can cause the P0339 DTC. Reminder! It’s also a good idea to check service information and TSBs on every vehicle you work on. After all, you don’t know what you don’t know. My technician checked the crank sensor and the circuit without finding any problems. After checking the vehicle for over an hour, my tech was still baffled on what the root cause of the misfire could be. He decided to ask me if I had any idea what was causing the problem since he could not pinpoint it.
I proceed to check all the basics from the battery, engine mechanical condition, ignition and fuel systems, as well as the CKP circuit, only to find the same results as my tech did. My suggestion was to perform a (Figure 3) Crank Relearn procedure on this vehicle since it’s the procedure that Acura/Honda recommends. I connected the MVCI along with the Honda factory software, showing and explaining the procedure to the technician so he could get a better understanding of the problem. Once the procedure was complete, the vehicle was road tested, then returned to the owner without any DTC or MIL illuminated. We assured the vehicle owner that her engine was in very good condition and all the issues were addressed. We explained that there was really nothing wrong with the work we performed on the engine, but by accident we forgot to perform the relearn procedure. The vehicle owner left our shop with a smile and even called us about 10 days later to tell us that the Accord was running great.