advice needed on engine fault

Ever since i have had my 2001 v6 galant the eml has been on, i heard that now a car will fail the mot if it is illuminated so thought i had best sort it. I had the codes read and it suggested the tps and the front bank oxygen sensor in the exhaust manifold. I changed both of these and after reseting the eml light, it came back on gggrrr. I have spoke to a few people now who have said fault codes are often misleading and you can spend a lot of money changing sensors for nothing. So my question is, the only possible thing i have noticed wrong with the engine is a slight surge and deceleration when crawling along in 1st or 2nd sometimes, other wise the engine is very quiet and smooth. Any suggestions in order of probability as to what would cause that and if it's a sensor where it is, Cheers.

Do you have Evoscan.
Do you have an odbII code reader.
Have you read the codes with the flashy dash method.
I ask about the code reader as yours is a 2001 galant and should be compliant with the odbii compliant. They are stupidly cheap to buy, so it would be rude not to.
This would be a good start.

Depending on the manufacture date of your car, it could have as many as four O2 sensors. Have you cleared the codes and seen if there are any new ones?

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Originally Posted by Davezj

Do you have Evoscan.
Do you have an odbII code reader.
Have you read the codes with the flashy dash method.
I ask about the code reader as yours is a 2001 galant and should be compliant with the odbii compliant. They are stupidly cheap to buy, so it would be rude not to.
This would be a good start.

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Hi Dave, the codes were read by a guy who drives round reading codes for his job, i don't know what reader he had but i think it was decent, it was a snap on reader with individual pcbs on a key ring for different makes of car. He plugged it in and it said there were 2 codes on there, one for the tps and one for the front manifold o2 sensor. He cleared the codes but when we started it back up the eml light came back on. I changed the tps and the front o2 sensor, then cleared the eml by disconn the batt for 10mins, then started it up, the eml light didn't come on at first so i thought it was cured, but on starting it a 2nd time the eml light came on.

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Originally Posted by elnevio

Depending on the manufacture date of your car, it could have as many as four O2 sensors. Have you cleared the codes and seen if there are any new ones?

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yeah i cleared them after fitting the new sensors, but the eml light came back on, i haven't checked to see if it has the same codes yet, i will have to get the guy back to plug his reader in.

You can check the errors yourself using nothing more than a paper clip, and will save you some money!

Check out the link in my signature (the "flashy dash" technique)

ok so i have got myself a cheap fault code reader, it is saying there are 2 codes, 2 pending, the codes are PO155 and PO135, they o2 sensor heater circuit malfunction, bank 2 sensor 1 and the o2 sensor heater circuit malfunction bank 1 sensor 1. But i have already changed the o2 sensor that is easily accessed on top of the front exhaust manifold and it still says it's malfunctioning, so could it be a dodgey connector that serves both sensors or something or is it that the sensors are ok but giving high readings because something else is wrong?

I've never confirmed which UK Galants were properly OBD-II compliant (but I believe it was around 2001). All 8G Galants have the OBD-II connector, but most use Mitsubishi's own MUT protocol. Generic fault readers will connect to the MUT cars, but usually spit out the wrong stuff.

To be sure, do the flashy dash technique that Garry has referred to, as this will be able to confirm whether the faults determined in this fashion are in agreement with what you have, or may provide additional (or different) codes completely!

Alright Nev, when I try to go to the link to the flashy dash test it says I don't have permission ?

thats because its in the paid members area. Membership helps to keep the site up and running by paying for the servers.

If you really don't want to support the site, someone will most likely provide the details on this thread so you can still check the fault codes. :happy:

If the car was first sold in Europe at 2001 it has to be odbll compliant.

If was imported then that is a different thing.

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Originally Posted by fylfot

ok so i have got myself a cheap fault code reader, it is saying there are 2 codes, 2 pending, the codes are PO155 and PO135, they o2 sensor heater circuit malfunction, bank 2 sensor 1 and the o2 sensor heater circuit malfunction bank 1 sensor 1. But i have already changed the o2 sensor that is easily accessed on top of the front exhaust manifold and it still says it's malfunctioning, so could it be a dodgey connector that serves both sensors or something or is it that the sensors are ok but giving high readings because something else is wrong?

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It could always be a wiring issue

I would check power and ground to both O2 sensors.
And before you ask for a wiring diagram there is a fully searchable PDF of the UK spec galant wiring schematic in the members area available for download.