Skoda Octavia 2.0 TDI

Featuring the Bosch EDC17C64 management system.

The Skoda Octavia emerged in the UK in 1998, with Vw-derived mechanical components on a platform shared with the Audi A3, VW Golf MKIV, SEAT Leon and Toledo. Second-generation models debuted in 2004, based on a platform shared with the contemporary Audi A3 and TT, SEAT Leon and VW Golf MKV models; these continued until 2013. The third-generation versions were longer, wider and had more interior space, yet were lighter than their predecessors. They were also packed with the latest technology and electronic safety systems.

A wide range of petrol and diesel power units were offered, including the 2.0-litre (1968cc) 16-valve, twin-overhead camshaft, common-rail turbocharged diesel motor (engine code CLCB) fitted to our guinea pig car, registered in March 2014. The vehicle employs a Bosch EDC17C64 management system and our guide to this model’s engine and its system is Edward Haggar. He’s using the Snap-on Verus Pro diagnostic tool.

Preparation

The engine management systems and running gear used in Skodas typically employs technology that has already been proven in Audis and other VAG models, meaning that any potential problems have usually been ironed out by the time they appear in Skodas.

Photograph 7 shows the wide band oxygen sensor, which usually features six cables. As explained in the accompanying caption, the wide band sensor acts so speedily that diagnosing problems using live data won’t help; an oscilloscope is essential for this. Nevertheless, when the sensor fails it triggers a fault code. The sensor is secured in position and a 22mm spanner is required for its removal.

Photograph 12 shows the battery monitoring system connection point; the ECU relies on precisely-controlled battery voltage in order to function

IMPORTANT: DO NOT JUMP-START THE VEHICLE BY CONNECTING CABLES DIRECTLY TO THE BATTERY POSTS, BUT INSTEAD USE THE JUMP START POSTS PROVIDED.

correctly. The system also knows when to use/control the alternator, so whereas on older vehicles the alternator is running all the time, on many new cars like this Skoda the unit is only brought into play when required. When checking for battery monitoring look at the negative terminal and you will see a small two-pin connector connection.

It is also essential to ensure that the correct type of battery is fitted – ie, an enhanced flooded battery (EFB) – to the recommended VAG specification.

Not shown in our photographs is the EGR valve, which is located very low down at the rear of the engine. This is a nightmare to access and deal with, if faulty; it could easily take five hours to sort out any problems.

The EGR and other sensors are coded to each individual vehicle, so recoding is necessary if a sensor is changed.

Fault 1:

EGR SYSTEM MALFUNCTIONS

When our first fault on this Octavia raises its head, the symptoms are a lack of power, plus illumination of the engine and glow plug warning lights. In the early stages of the problem it’s possible that the driver will be able to ‘cycle’ the ignition and the system will reset, but if left to its own devices the car will become undriveable. Usually, the problem lies with the failure of the EGR valve system circuitry, not the valve itself.

Please note that on these engines it’s not possible to blank off the EGR valve, due to it incorporating a position ‘feed back’, and doing so will confuse the ECU even more. A popular alternative these days is to delete the EGR from the ECU and map it out, but caution should be taken if considering undertaking this – if found out, such a move will invalidate the vehicle warranty; with some diagnostic tools, it’s possible to read if a vehicle has been mapped.

The EGR is difficult to access, located right at the back of the engine and below the turbocharger, and all work on it has to be carried out from underneath the car, so you will need a ramp. Our recommendation is to remove the righthand side driveshaft to provide better access, but some say that the job can be done with the driveshaft in place. However, you should note that some EGRS are located at the top of the engine.

When performing the initial diagnostic assessment, it will be found that numerous EGR codes will be stored, but upon clearing them, they will come straight back. If your test machine provides the facility, it is worth carrying out an EGR performance test in ‘Special Functions’, but not all diagnostic readers have this feature. Another thing to note is that the EGR valve will require calibration, but most testers can do this.

When changing the EGR valve, the cooler needs to be renewed at the same time. The genuine VAG EGR valve is just as cheap as aftermarket components. According to our local VAG parts supplier, the EGR valve is their biggest seller – so that’s a sign of how often they fail!

Fault 2:

DPF PRESSURE SENSOR FAILURE

In this case, the vehicle will still drive well initially, but the engine warning light will be illuminated intermittently. Carrying out a full diagnostics assessment will show numerous codes relating to the DPF and pressure.

It should be noted that a blocked EGR valve can cause a blocked DPF, so this needs to be eliminated in the diagnostic process. An initial check should be to look at the DPF live data and check for DPF content, which will show in the form of a percentage. Anything above 70% means that you won’t be able to regenerate the system, so removal and cleaning of the filter is required or a new filter needs to be fitted. DPFS are generally good and they don’t just fail – something else usually causes them to clog.

Again looking at live data, check the pressure readings. A tell-tale sign of this fault will be pressure figures that jump around with key on, engine off. Flick the sensor and check the live data – if you see the pressure reading jump, this is another sign of a faulty sensor. Always remove the sensor and try cleaning it before renewing – it’s very common for them to clog with soot. A small amount of brake or carburettor cleaner on a cotton wool bud is the easiest approach, but work with caution when cleaning as the sensors are delicate.

In addition to the sensor itself, also check the pipework to the sensor – this can come adrift and melt or else

get tangled up in the engine bay. No calibration is required when a new sensor is fitted, but another check of the live data should show no fluctuations in readings.

Fault 3:

STEERING ANGLE SENSOR FAILURE/ INCORRECT STEERING ANGLE CALIBRATION

Symptoms of our third fault on the Octavia are that the ABS, traction control system and steering warning lights will be illuminated. It’s likely that these lights will appear after some repairs have been carried out relating to the battery – possible the battery’s gone dead and the vehicle has been jumpstarted or else the battery has been removed for repairs.

What happens is that the ECU ‘loses’ the position of the steering wheel and gets confused by the feedback. Another trigger can be that the vehicle has undergone a tracking check, but has not been properly set. Questions should be asked about any repairs that have taken place recently.

Carrying out a diagnostic check will reveal a steering angle fault code, but trying to delete the code won’t work. The system will require a steering angle calibration, a very simple operation that most test equipment can carry out.

The steering angle sensor (fitted to the top of the steering column) can also fail, but nine times out of 10 incorrect calibration is the cause of the trouble.

Another fault that will cause the ABS light to be illuminated is an incorrect tyre fitted to one side of the car; the code will be ‘ABS sensor signal coherence’.

Fault 4:

IMMOBILISER/KEY DIFFICULTIES

VAG keys are very, very delicate and need to be treated with exceptional care.

You might be presented with a vehicle that doesn’t start and, if so equipped, a key light will be flashing on the dash.

Carrying out diagnostic testing will indicate immobiliser codes and start signals. If your diagnostic equipment allows, check the live data and see if the key signal is present. If not, it’s likely that the key might have been dropped onto a hard surface. It’s worth opening up the key and checking for signs of damage; you might be able to carry out a repair. If a second key is handy, it’s worth checking whether that starts the vehicle. If a new key is needed, a mobile locksmith or a trip to the dealer is required and it can get expensive.