Car Mechanics (UK) - - Elec­tronic Di­ag­nos­tics Volvo V40 2.0d -

Fault 1:


When this prob­lem oc­curs, it is likely that the engine man­age­ment warn­ing lamp will be il­lu­mi­nated. Also, de­pend­ing on the po­si­tion in which the actuator has failed, a lack of power will al­most cer­tainly also be ev­i­dent.

Car­ry­ing out a di­ag­nos­tic check may re­veal a wide va­ri­ety of pos­si­ble fault codes (too many to list here in to­tal­ity). Here are some ex­am­ples of the codes that may ap­pear:

P0403 ‘Ex­haust gas re­cir­cu­la­tion (EGR) cir­cuit mal­func­tion’, with pos­si­ble causes of the trou­ble in­clud­ing the wiring, the EGR (Ex­haust Gas Re­cir­cu­la­tion) so­le­noid and the ECM (Engine Con­trol Mo­d­ule).

P042E ‘EGR valve actuator – stuck open’, pos­si­ble cul­prits be­ing the wiring, EGR valve actuator, the ECM or a me­chan­i­cal prob­lem.

P042F ‘EGR valve actuator – stuck closed’, pos­si­ble cul­prits be­ing the wiring, EGR valve actuator, the ECM or a me­chan­i­cal prob­lem.

P04FA ‘EGR – a com­po­nent or sys­tem over-tem­per­a­ture con­di­tion’, pos­si­ble rea­sons be­ing trace­able to the EGR cooler or EGR valve.

In­evitably the fault will lie with the EGR valve actuator. If avail­able on your di­ag­nos­tic equip­ment, in ‘special func­tions’, se­lect ‘EGR’, then ac­ti­vate… This takes over the ECU and op­er­ates the valves. You should hear and see move­ment; a sim­ple re­sis­tance check on Pins 1 and 5 with the con­nec­tor dis­con­nected should show 4 ohms – any­thing higher than this will in­di­cate a fail­ure.

Ed­ward ad­vises that re­newal of the actuator is fairly easy, but you have to carry out a ‘teach­ing’ process once the new unit has been fit­ted.

Fault 2:


In this prob­lem­atic sit­u­a­tion, the car’s driver will al­most cer­tainly no­tice a lack of power and engine man­age­ment dif­fi­cul­ties, with the DPF warn­ing light il­lu­mi­nated, and with fault codes C1B14 and C1B15 stored.

The sen­sor can do funny things when it fails; you have to re­mem­ber its pur­pose is to tell the ECU how full the DPF is, via a pres­sure to volt­age sig­nal. So, it’s pos­si­ble it might be re­gen­er­at­ing more of­ten than it should, or to the un­trained eye a new DPF fil­ter will need to be fit­ted.

Firstly, if avail­able look at live data… in Ed­ward’s ex­pe­ri­ence the sig­nals jump around. It’s also pos­si­ble that by us­ing a mul­ti­me­ter you can check the sig­nalling. Re­mem­ber that the higher the volt­age the more blocked the fil­ter is, ie. 0 volts means ‘empty’; 5 volts in­di­cates ‘blocked’. Al­ways fit good qual­ity new sen­sors – there are many poorly man­u­fac­tured copies avail­able, and they can cause more trou­ble than good.


This is a prob­lem that al­most cer­tainly won’t pro­duce any lack of power but if the fault is left to its own de­vices it will cre­ate a prob­lem in terms of the DPF fill­ing and block­ing…

The fault lies with the glow plugs. You have to re­mem­ber that mod­ern sys­tems won’t carry out a re­gen­er­a­tion while faults are stored in the engine con­trol sys­tem. Widely, peo­ple are of the mind­set that be­cause the car is start­ing OK the glow plugs don’t need to be re­newed.

How­ever… Yes, glow plugs, in cer­tain tem­per­a­ture ranges, help cold start­ing and they aid emis­sion re­duc­tions, but this is not the whole story…

Car­ry­ing out a fault code check will show a fault code for the failed cylin­der; be wary if you have codes set for all the cylin­ders as this can be a red her­ring and a fault with the con­troller. Note that a sin­gle cylin­der code re­lates to the glow plug it­self.

When test­ing, the re­quired re­sis­tance for a good con­di­tion com­po­nent, work­ing as it should, is 0.4 ohms.

Ed­ward al­ways rec­om­mends in­stalling a com­plete set of glow plugs be­cause it’s likely that if one fails the oth­ers might not be far be­hind.

A good soak­ing in pen­e­trat­ing fluid be­fore you at­tempt re­moval helps en­sure a pos­i­tive re­sult!

Fault 4:


Many ex­am­ples of the Volvo V40/ford Fo­cus from the era un­der re­view suf­fer from re­ally bad con­den­sa­tion in both the front head­lamps – the prob­lem be­ing poor ven­ti­la­tion within the lamp units.

A re­ally sim­ply fix is to re­move the rear lamp cover (the one that pro­vides ac­cess to the bulbs) and add two small holes for fur­ther ven­ti­la­tion –

“This works a treat”, says Ed­ward.

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