Electronic Diagnostics: Volvo XC70 2.4d
The first series Volvo V70 estates were introduced in 1996, having evolved from the 850 estates. The four-wheel drive Cross Country versions made their debut at the 1997 Frankfurt Motor Show. A considerably upgraded secondgeneration V70 and four-wheel drive V70 XC models arrived in 2000, with the latter renamed XC70 in 2003.
From 2007 until 2016, much revised third-generation models continued the Volvo estate theme, with all versions notable for their dynamic competence and comfortable accommodation for passengers, plus a large load area. In fact, space for passengers and luggage was even greater than in the predecessors.
A variety of petrol and diesel engines were offered. For this feature we are looking at a 2.4-litre five-cylinder dieselpowered example, first registered in June
2013. Our guide to the diagnostic aspects of this engine and its Bosch EDC17 management system is Edward Haggar. Preparation For reliable operation and good performance, it’s essential for all servicing aspects to be addressed. If the car you are dealing with has no known maintenance history or has not been serviced recently, our recommendation is to carry out a full assessment and service.
In addition to ensuring that the engine oil and filter are renewed, using only oil as recommended by Volvo, and with a high-quality filter to original equipment specification, it is wise to renew the air and fuel filters. Again, always use highquality filters to original equipment level. Note that a choked fuel filter can lead to poor running due to a restricted supply of fuel to the engine.
It is a good idea to check frequently for deterioration of the underbonnet hoses/ pipework, paying special attention to the rubber pipes serving the intercooler. If these are split or leaking, the engine will be low on power (see Fault 1: Intercooler/ pipework issues).
Fault 1
INTERCOOLER/ PIPEWORK ISSUES
This first fault won’t require the use of a diagnostic tool. Symptoms include the engine feeling down on power, plus the possibility of black smoke from the exhaust. Inspect the engine bay, looking at all the rubber intercooler pipes – you will likely see a split in the pipe and oily residue. As a temporary fix the pipe can be taped up, but a replacement hose will be needed.
If you wanted to approach it from a diagnostic view, you can carry out a fault code check and you will likely see codes relating to air mass or boost pressure, but because the split pipe is allowing air leaks it confuses the ECU.
Another area to inspect for leaks is the metal intercooler itself – its location low down at the front of the vehicle is susceptible to holes caused by stone damage. Even a pinprick hole somewhere in the system can cause the ECU to apply ‘limp-home’ mode. Replacement pipes are readily available at most Volvo dealers.
Fault 2
FAULTY DPF PRESSURE SENSOR
When this fault is present, the driver may not be aware of it until the car becomes virtually undriveable. At this stage, it feels as if somebody is squeezing the fuel line and there’s no power. In addition, the engine management light will illuminate, with numerous codes stored relating to the diesel particulate filter (DPF). The DPF will not have been carrying out a regeneration and the filter will have become blocked.
The problem is due to a faulty pressure sensor. A simple multimeter can be used to check voltage at the sensor, which should read 0.5 volts when the filter is empty and 5 volts when it’s full. In general, when the sensor fails it will be stuck on 0.5-1 volts, when actually the DPF is blocked, so the reading should be nearer 5 volts. However, be aware that the other wire to the sensor is the 5-volt supply.
Renewing the sensor simply involves disconnecting two pipes and a clip.
Fault 3 FAULTY EGR VALVE
Depending on the way in which the next fault occurs the driver might or might not have an engine warning light illuminated, or the car may suffer from extended cranking/starting or poor performance. The fault is actually with the exhaust gas recirculation (EGR) valve. Carry out an initial fault code check and you will find the code ‘P140700 – EGR no flow’. You could try removing the valve to clean it, as it’s fairly easy to access.
Use your tester to read off the EGR live data. The valve probably won’t operate, indicating a fault. Some diagnostic tools come with an EGR function, in which the ECU tries to operate the valve while carrying out a self-test function with a simple pass or fail result.
Fault 4 BLOCKED FUEL FILTER
When our fourth fault is present the Volvo will not drive properly as the fuel supply is being restricted. In such situations it’s always worth looking first at the diesel fuel filter. We have heard of vehicles on which garages have spent hundreds – and sometimes thousands – of pounds trying to fix a fault that turns out to be nothing more than a blockage in the filter.
This problem doesn’t just affect Volvos, but vehicles from all manufacturers. If there’s no service history with the vehicle or you can’t see a new filter, it should be changed regardless. People often assume that with the manufacturerrecommended high mileage/time intervals between services these days, the filters just don’t need changing, but in our experience they still do.