ECU testing & fault codes

HI

i recently tried shorting the 2 pins as suggested to test for fault codes @2000rpm but mines is showing code 55 no faults (5 long flashes and 5 short flashes) now when i let the engine tick over @8-900 rpm i got other flash readings, this was like 1 long flash and a short flash then it kinda went different 2 long flashes 1 short 1...(little confused on this one). does this mean that all the sensors ie lambda sensor is working fine! there is a rich smell from exhaust fumes like strong petrol any suggestions. the reason i ask is im only getting about 30 miles per £6 of fuel (i know its a weird amount but thats what i put in for my readings) all driving is local and not motorway.

im going to double check it again should i leave the engine running for a few minutes first before i do the check again? im gonna post a link for youtube for you guys to see later.

ive read posts regarding the lambda sensor, should i take it off and clean it?

maybe im expecting too much for local driving but is 30 miles ok for £6 of fuel plus the redex im using too!

regards
 

pollyp

Club Member
when you turn on Ign and short the 2 pins it goes into diagnostic readout mode hence 5long & 5short flash for normal. when the then start the engine warmed up and hold at 2000, the light should flash at 1/2sec intervals. if it responds slower or inconsistant then the sensor might be dirty or worn.

dirt would usually be burnt away by the hot exhaust or sensor heater but if it can't get hot fast enough during cold runs from faulty sensor heater (or engine not given chance to fully heat up by short runs), contaminants could build up inside. if it gets too hot maybe from lean mixture, the contaminants could fuse a coating over the sensor impeding its operation

i usually just replace em (motor factors or scrappy) when they're sluggish
 
OP
OP
K
hi

i managed to take off the lambda sensor at exhaust. when looking at the nipple part it has grooved slats now i noticed that the bottom near the screw end was full of soot (black stuff) so cleaned the the whole part and came up shinny metal again. will i noticed any kind of difference when starting engine or will i just check my fuel consumption over next fill up to see if it has worked. when i start the car it revs to about 1250 rpm then gradually dips down to about 750-800 rpm when idling.

time will tell if the fuel consumption is better!

regards
 

pollyp

Club Member
sounds normal. the idle valve initially opens to speed up the cold engine and closes when warm, lowering it to 750rpm.

the groove opening and internal sensor bit of the sensor is more important to clean than the outer casing. the inner sensor is kinda tricky to clean correctly, some other forum said brake cleaner but i dunno. do a fuel trial and see if milage improves.

if its still 25mpg, best replace the sensor. tis only £50 and i've calculated that it'll repay for itself after bout 4 fill ups or 1000miles if motorway milage improves from 25 to 40mpg
 
OP
OP
K
if its still 25mpg, best replace the sensor. tis only £50 and i've calculated that it'll repay for itself after bout 4 fill ups or 1000miles if motorway milage improves from 25 to 40mpg

polly when you say if motorway driving improves from 25mpg to 40mpg does that mean that 25mpg around town is ok? or does it mean that even if the sensor is knackered you get the same mpg if its town or motorway!

regards
 

pollyp

Club Member
i thought ya meant 25mpg motorways. i get 35mpg urban and 45mpg motorways. if milage is below 30mpg under normal driving then the lambda is usually stuffed.
 
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