Elec­tronic Diagnostics: BMW 1-Se­ries 2.0 petrol

Siemens Motronic MSD80 sys­tem.

Car Mechanics (UK) - - Contents -

Pop­u­lar due to their driv­ing char­ac­ter­is­tics, BMW’S 1-Se­ries 2.0-litre petrol models can suf­fer from their fair share of di­ag­nos­tic dif­fi­cul­ties. Kim Henson and

Edward Hag­gar take a close look.

Ar­riv­ing in 2004 and re­plac­ing the 3-Se­ries Com­pact as the small­est model in BMW’S line-up, the 1-Se­ries con­tin­ued the com­pany’s tra­di­tional ap­proach of em­ploy­ing a lon­gi­tu­di­nally-mounted front en­gine/gear­box driv­ing the back wheels. This pro­vided an im­pres­sive 50:50 weight bal­ance be­tween the front and rear of the car for good driv­ing dy­nam­ics, helped by a multi-link alu­minium rear sus­pen­sion set-up.

The BMW model des­ig­na­tions were the E81 (three-door hatch­back), E87 (five-door hatch­back) and, from 2007, E82 (two-door coupé) and E88 (con­vert­ible). The range was facelifted in 2007 and 2011. En­gine choices were be­tween four- or six-cylin­der petrolpow­ered units and four-cylin­der diesels.

The 1-Se­ries models have proved pop­u­lar as a rel­a­tively af­ford­able way into BMW own­er­ship. Sec­ond­gen­er­a­tion models ar­rived in 2013.

Our car is a 2008 E87 118 2.0-litre petrol model with the en­gine code N43B20A. A Siemens Motronic MSD80 man­age­ment sys­tem is em­ployed.

Our guide to this model’s en­gine and its sys­tem is Edward Hag­gar.


With these BMWS, the driver is able to tell via the dash­board/di­ag­nos­tic equip­ment when ser­vic­ing com­po­nents are due for chang­ing. How­ever, note that it is very easy to ac­ci­den­tally re­set the intervals on the dash, and we have heard of in­ci­dents where all of the ser­vice in­for­ma­tion in­di­ca­tors were re­set at once, giv­ing the false im­pres­sion that the car had re­cently been fully ser­viced.

These en­gines are not equipped with an oil dip­stick, but there’s a dash­mounted oil level lamp, in ad­di­tion to which there is also an oil pres­sure warn­ing lamp. When the oil level warn­ing lamp il­lu­mi­nates, own­ers some­times

misiden­tify this as the oil pres­sure warn­ing lamp. If the red pres­sure warn­ing light on the dash il­lu­mi­nates, by the time it comes on, dam­age to the en­gine may al­ready have re­sulted.

You need to be aware that the ig­ni­tion lock set-up will only work for a lim­ited, pre-set num­ber of ac­ti­va­tions, af­ter which it will fail. This is bad news as the ve­hi­cle can let you down at any time and, in the worst-case sce­nario, the car may need a new ig­ni­tion lock as­sem­bly, cost­ing about £1000.

The op­er­a­tion of the VANOS vari­able valve tim­ing sys­tem needs to be checked. If di­ag­nos­tic in­ter­ro­ga­tion re­veals fault codes re­lat­ing to the VANOS set-up, it is worth re­mov­ing and clean­ing the as­sem­bly us­ing a non-ag­gres­sive sol­vent. If there is any oil leak­ing from the VANOS unit, it sim­ply re­quires a new seal kit.

Fault 1


This fault has many symp­toms, rang­ing from the warn­ing lamp il­lu­mi­nat­ing on am­ber to the ex­treme case of a ve­hi­cle re­fus­ing to start.

In cer­tain cases a dis­charged bat­tery will be the cul­prit – these days, as with most mod­ern cars, hav­ing the cor­rect bat­tery volt­age avail­able is a must. How­ever, the ma­jor­ity of the time, the prob­lem lies with a built-in ‘counter’ sys­tem, pre-set by BMW, so that the ig­ni­tion/steer­ing lock op­er­ates only for 1000 ac­tu­a­tions, which can then leave the driver stranded in a no-start sit­u­a­tion. Es­sen­tially what hap­pens is that af­ter

NOTES: 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.

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