AFT_B009

A fault code can tell you a lot, if you understand what it is telling you. Then again, it can also leave you questioning what it means and what is causing it to be set if you don’t know why it has logged in the first place. A recent job I had backs up the importance of knowing what the information is telling you. Turbo boost pressure The vehicle was a 2008 Vauxhall Antara 2.0 Diesel, which belonged to my neighbour Gordon. One evening, having a chat over the fence, he said he had been having running issues. After his local garage plugged into it, they changed some parts based on fault codes they found, but it was no better. The vehicle logged turbo boost pressure fault codes under load, and had slowly got worse and worse to the point it was now as flat as a pancake and had no power at all. I offered to bring some tools home and plug it in and have a quick look one night, and then offer some advice on where to go next as a favour. After all, on several occasions he had helped me out with one thing or another. Plugging in my Snap-On Zeus, the one that was part of my prize when I won Top Technician 2019, I was presented with the a number of fault codes (see Fig.1). Upon asking some questions, he told me that the vehicle repeatedly logged faults for turbo boost pressure, so the boost pressure sensor (MAP) had been replaced but the vehicle still had the same symptoms. The EGR valve vacuum control solenoid had also been replaced as it had fallen apart, and on removal the old one had signs it had been broken and repaired. Reviewing the situation, we have six faults stored on initial inspection. What I like to do here is split the faults into groups of what could be related to the customer’s complaint and what can be left for now and diagnosed/repaired further down the line. Grouping faults My groups, based on my findings, were that the P0101, P0045, P0069 and P0299 faults were directly related to the lack of power complaint. I also surmised that the fuel level fault and glow plug fault were secondary faults which required attention after the initial four faults had been rectified. After a quick visual inspection under the bonnet, this vehicle was equipped with a DPF so the glow plug fault would require attention sooner rather than later. I decided to leave the fuel fault, as in my experience this wouldn’t cause the customer complaint. However, like everything, there will be cases with certain manufacturers where a similar fault code could cause a running fault. This means it’s always a good idea not to ignore every fault code stored. With the faults, I wanted to focus so now I broke them down one by one by what they meant and what could cause them to set. This was done with a mix of technical information and my own personal knowledge. My list was as follows; P0101 – Intake air system leak detected: This fault is logged in relation to the mass air flow sensor and it is because the engine control unit detects that the measured MAF is not within range of the calculated model in the software that is derived from the boost pressure sensor, which remember is new. For this fault I would compare live data from the MAF and MAP to see if either were incorrect. P0045 – Boost pressure valve low voltage: This fault is logged either by a short to ground in the circuit or an 22 AFTERMARKET SEPTEMBER 2020 TECHNICAL Below: Vauxhall Antara www.aftermarketonline.net FAULT CODES: CRACKING THE NUT A recent job undertaken by Neil backs up the importance of knowing what a fault code means, and what that information can tell you BY Neil Currie