Fiat 500L 1.6 Mul­ti­jet

Diesel with Bosch man­age­ment.

Car Mechanics (UK) - - Contents -

In­tro­duced in 2007, Fiat’s 500 has been a huge hit and there have been a num­ber of dif­fer­ent ver­sions based on the orig­i­nal model. One of th­ese is the 500L, de­vel­op­ment of which started in 2010 to pro­vide a more spa­cious MPV on a com­pact plat­form. It shares many sim­i­lar­i­ties with the Jeep Rene­gade.

The new­comer was in­tended to re­place the Fiat Idea and was de­signed around the Fiat/gm ‘Small Plat­form’. It emerged at the Geneva Mo­tor Show in 2012, fea­tur­ing a cab for­ward de­sign, in which the em­pha­sis is on in­te­rior space. A ma­jor plus point is the so-called Magic Cargo Space, in­cor­po­rat­ing a tripleleve­l load com­part­ment floor, rear seats that slide, fold and tum­ble, and a front pas­sen­ger seat that folds flat.

A va­ri­ety of en­gines have been of­fered, in­clud­ing Fiat’s twin-cylin­der Twin Air petrol units, a four-cylin­der petrol en­gine and Mul­ti­jet II com­mon-rail diesel, in four-cylin­der 1.3 and 1.6-litre forms. Fur­ther en­gine op­tions ar­rived in 2014.

Hav­ing made their de­but in 2003, Fiat’s Mul­ti­jet diesel en­gines em­ploy five rapid in­jec­tions of fuel per cy­cle, in­tro­duced un­der very high pres­sure, en­abling quiet, fuel-ef­fi­cient com­bus­tion. The Mul­ti­jet II units, first in­tro­duced in 2009, are even more ad­vanced and fea­ture new in­jec­tors de­liv­er­ing eight in­jec­tions per cy­cle, plus higher fuel de­liv­ery pres­sure, re­sult­ing in even more pre­cise op­er­a­tion.

Our car here was reg­is­tered in June 2013 with the en­gine (code 199B5.000) con­trolled by a Bosch man­age­ment sys­tem. Our guide to this model’s en­gine and its sys­tem is Ed­ward Hag­gar.


For re­li­able long-term op­er­a­tion, it is es­sen­tial that en­gine main­te­nance is car­ried out reg­u­larly. When in­stalling a new air fil­ter el­e­ment, al­ways en­sure that the re­place­ment el­e­ment is of good qual­ity, be­cause in­fe­rior types tend to break up, re­sult­ing in de­bris that af­fects the per­for­mance of the air mass sen­sor.

Note that when­ever the diesel fil­ter is re­newed, an in-line pump should be used to aid the bleed­ing of air from the sys­tem. Fail­ure to do this will re­sult in ex­ces­sive en­gine crank­ing, which can dam­age the starter mo­tor. There is also a risk of in­ter­nal dam­age within the fuel sys­tem, caused by the lack of diesel fuel which nor­mally lu­bri­cates the sys­tem in­ter­nally.

Th­ese en­gines are prone to suf­fer­ing from wa­ter pump fail­ure, which may re­sult in the cam/wa­ter pump drive­belt jump­ing, caus­ing cat­a­strophic fail­ure of the en­gine. Very of­ten the cam­belt is re­newed but the old wa­ter pump is left alone.

Fault 1:


Symp­toms of our first fault in­clude a lack of power/poor throt­tle re­sponse, and the en­gine may crank for an ex­tended time but refuse to start. Stored codes may re­late to too much or too lit­tle air mass trans­fer through the en­gine. Equally it is pos­si­ble that no codes have been reg­is­tered, in which case live data should be con­sulted, look­ing at air mass as­pects. The pre­cise num­bers aren’t as im­por­tant as see­ing a fig­ure to in­di­cate move­ment of air mass through the en­gine.

If a lack of air flow is con­firmed, de­tach the in­take trunk­ing and un­bolt the throt­tle flap assem­bly for close in­spec­tion. Once the assem­bly is re­moved from the en­gine, take care to en­sure that the flap is not ro­tated vi­o­lently nor through a large an­gle; min­i­mal move­ment is best.

The throt­tle flap tends to stick in the closed po­si­tion, re­sult­ing in the above symp­toms. This can be ad­dressed by the use of a car­bu­ret­tor/throt­tle cleaner fluid (which should not be too ag­gres­sive in na­ture, to avoid com­po­nent dam­age) ap­plied care­fully to and around the flap by means of a cot­ton wool bud or sim­i­lar.

Some test equip­ment in­cor­po­rates an ‘ac­tu­a­tor test’ func­tion, in this in­stance en­abling checks to be car­ried out to con­firm that the flap fully opens and closes as de­signed – very use­ful af­ter clean­ing op­er­a­tions have been un­der­taken. Once re­assem­bly has been car­ried out, re-learn­ing op­er­a­tions are re­quired, and this job can be tack­led by most di­ag­nos­tic test equip­ment.

In many cases it will im­me­di­ately be no­tice­able how much more re­spon­sive the ve­hi­cle has be­come, since the en­gine will once again be op­er­at­ing in line with the orig­i­nal fac­tory set­tings. Over time the ECU will ad­just to a grad­u­ally de­te­ri­o­rat­ing sit­u­a­tion in which the throt­tle flap is start­ing to stick, etc, so the car will still run, but be­low op­ti­mum per­for­mance lev­els.

Fault 2:


When our next fault arises, the driver may no­tice a burn­ing smell. Ini­tially the car will still be drive­able, but even­tu­ally the oil warn­ing lamp will il­lu­mi­nate and, if you con­tinue to drive the car, the ECU will shut down the en­gine com­pletely.

What is hap­pen­ing is that the DPF keeps re­gen­er­at­ing it­self and a sen­sor within the en­gine oil senses this, which re­duces the ef­fec­tive­ness of the oil. The mo­tor is closed down to pre­vent dam­age.

A di­ag­nos­tic check may re­veal fault codes re­lat­ing to DPF pres­sure. Depend­ing on the test ma­chine, it should be pos­si­ble to view live data, and a pres­sure read­ing across the DPF of about 0.2 Bar should be seen; read­ings any higher than this in­di­cates a block­age within the fil­ter.

The root cause of this is likely to lie within the ECU soft­ware. The sit­u­a­tion is most likely to arise in cars that have not seen a deal­er­ship work­shop in a long time, since Fiat is­sued ECU soft­ware up­dates to deal­ers to cope with this prob­lem.

The ECU can be re­pro­grammed – or the car can be re­turned to Fiat for a new ECU – al­though Fiat’s pos­i­tive re­sponse to a car that has not been dealer-main­tained can­not be guar­an­teed.

We rec­om­mend send­ing off the car’s ECU to have the unit re­man­u­fac­tured. On its re­turn, the unit can be plugged straight back into the ve­hi­cle. Con­versely, if a new ECU is fit­ted, it will need to be pro­grammed by Fiat, an in­de­pen­dent di­ag­nos­tic spe­cial­ist or a lock­smith.

Alas, this is not the end of po­ten­tially ex­pen­sive prob­lems, for the DPF also needs to be re­moved from the ve­hi­cle and checked. It is highly likely that

dam­age will have oc­curred within the unit, ne­ces­si­tat­ing a re­place­ment at a cost of around £800 for the DPF alone.

Fault 3:


Symp­toms of this prob­lem are a ve­hi­cle that is re­luc­tant to start, al­though in the early stages, the car’s drive­abil­ity may seem fine. How­ever, the man­ner in which the car drives will de­te­ri­o­rate as the prob­lem – due to in­jec­tor mal­func­tions – be­comes more se­ri­ous.

Di­ag­nos­tic in­ter­ro­ga­tion may re­veal fault codes re­lat­ing to the in­jec­tor cir­cuit or fuel flow, al­though not nec­es­sar­ily ex­ces­sive fuel flow, and the codes won’t al­ways be cylin­der-spe­cific.

Live data can be used to ob­serve and com­pare the ef­fi­ciency of all four in­jec­tors. It may be ev­i­dent that one or more of the in­jec­tors is de­liv­er­ing sig­nif­i­cantly more fuel than the rest. A diesel leak-off test can also be car­ried out to as­cer­tain how much leak-off is be­ing drawn off at the in­jec­tors. Gen­er­ally, a faulty in­jec­tor leaks off at about twice the rate of a healthy one. When in­stalling new or re­con­di­tioned

in­jec­tors, al­ways re­new their cop­per seals at the same time. It is good prac­tice to re­new all four in­jec­tors at the same time, even though they cost around £200 each.

New or old in­jec­tors will need to be re­pro­grammed on in­stal­la­tion, us­ing the iden­ti­fi­ca­tion num­ber shown at the top of each in­jec­tor. It is pos­si­ble that the ECU may lose the orig­i­nal codes. Al­though the en­gine will run if re­pro­gram­ming is not car­ried out, this pro­ce­dure is ad­vis­able to ob­tain op­ti­mum per­for­mance and fuel econ­omy. It is also wise to re­new the fuel fil­ter in con­junc­tion with the in­jec­tors. If a faulty in­jec­tor is iden­ti­fied, the fuel fil­ter hous­ing should be closely ex­am­ined for signs of de­bris/fil­ings, which can clog the fil­ter and dam­age the in­jec­tors.

Fault 4:


In the early stages of this prob­lem, the man­age­ment sys­tem warn­ing lamp may il­lu­mi­nate, but at first there will be no dif­fi­cul­ties in terms of drive­abil­ity. A di­ag­nos­tic in­ter­ro­ga­tion may bring up fault codes re­lat­ing to Egr/flow, due to soot­ing-up of the EGR valve.

If the prob­lem hasn’t reached a se­ri­ous stage, clear­ing the fault codes and us­ing a good-qual­ity diesel fuel ad­di­tive may do the trick. How­ever, if the fault is left to its own de­vices, the valve will con­tinue to soot up and the en­gine will lose power or may even be­come im­pos­si­ble to rev at all.

Un­for­tu­nately, the valve’s buried lo­ca­tion does not help when it comes to ac­cess­ing and clean­ing it, be­ing tucked away be­low the ex­haust man­i­fold. The valve in­cor­po­rates a built-in cooler to help re­duce emis­sions. How­ever, the cooler adds to the cost of re­new­ing – be­tween £300-400. For­tu­nately, it’s not a dealer-only com­po­nent.

In our ex­pe­ri­ence, if a valve is cleaned, in 90% of cases it will soon need to be re­newed any­way. There­fore, in view of its in­ac­ces­si­bil­ity, re­new the unit re­gard­less.

When a new valve is in­stalled, it will be nec­es­sary for adap­tions to be re­learned, in or­der to re­store the man­u­fac­turer’s orig­i­nal set­tings. Live data can be used to op­er­ate the valve – which is ac­ti­vated elec­tron­i­cally rather than, for ex­am­ple, op­er­ated by vac­uum – to en­sure that it fully opens and closes as de­signed.

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