Electronic Diagnostics: Peugeot 107 1.0

Edward Haggar

Kim Henson

Introduced in the summer of 2005, the four-seater Peugeot 107 city car was developed in conjunction with near-identical badge-engineered vehicles from Citroën (C1) and Toyota (Aygo). The compact newcomer was offered with three or five doors, and power unit choices were between a three-cylinder 1.0-litre petrol engine and a four-cylinder 1.4-litre HDI diesel.

A raft of cosmetic and engineering changes in 2009 resulted in mild restyling, interior upgrades and slightly lower engine emissions, plus marginally improved fuel consumption. The 108 arrived in 2014, ousting the 107.

The 107 featured here is owned by the editor and was registered in November 2007. It’s powered by the 998cc petrol unit. Our diagnostic guide to this 107 and its Bosch Motronic ME7.9.5 management system is Edward Haggar.

As far as repairs and servicing goes these 107s have got to be among the easiest modern cars to work on. Even a clutch change can be carried out by a home mechanic. The engine is fitted with a timing chain, so there are no routine belt changes to consider.

These engines are very reliable. Edward says that he has a customer whose 107 has so far covered 165,000 miles and still on its original engine internals. The owners allow him to change the engine oil every five months or 5000 miles (whichever comes first) to maintain reliability.

Edward advises that the trick with these diminutive motors is to keep on top of things – and, of course, regular maintenance is a big help.

A simple diagnostic check will show ‘C1554 power steering malfunction’. The problem lies internally within the steering ECU, which is located above the pedals. You can opt for a new ECU – but this route is expensive and coding is required. By contrast, Edward uses an ECU repair company that provides a quick repair turnaround and this option is a simple plug-and-play fix, which also comes with a lifetime guarantee.

Fault 2:

leaks or restrictions. A smoke test of the intake system is a useful quick check here; if that’s all okay then carry out testing on the MAP sensor.

It’s worth looking at live data for the MAP sensor. In key-on mode, in theory the reading should be as close to 0 as possible – anything higher suggests a faulty sensor.

You need to remove the air filter housing – first releasing the two

‘squeeze’ clips. You should then see the MAP sensor at the back of the throttle body, held by two bolts (10mm). You could just remove and clean it if no diagnostic equipment is available; carefully use a cotton wool bud with a light proprietary cleaning fluid/spray.

If available use a multimeter set to ‘voltage’ with negative on negative battery post; the positive cable from multimeter back probing pin 1 should read 1.2-2 volts. 

This fault can show itself in numerous ways: notably the engine may start only after extended cranking, or can cut out when running. The fault lies with the fuel pump – or more importantly – the filter inside it.

First, you could connect an amp clamp to the fuel pump fuse and check current draw to see if the pump is drawing more current than it should be, ie working harder due to being blocked – or it could

Oxygen sensor heater circuit pins 1 and 2

Crank sensor

Value 12 ohms 0.3-0.8 ohms 4-16 ohms

1850-2450 ohms

+

Y81

All references in our text and captions to ‘left’ and right’ sides are from the point of view of someone sitting in the car and looking ahead.

Tucked behind the battery and just inboard of the left-hand front suspension tower, is the underbonnet fuse and relay box, which is normally covered by a protective lid. Make sure that the lid is always correctly and fully fitted, to keep out moisture. Three cylinders means three separate ignition coils on this engine (and spark plugs below), all accessibly positioned at the top of the engine, and usually hidden by a plastic cover panel. Ensure that the coils are secure (each held with one 10mm nut), in good physical condition and with sound cables/connections.