How To: Check & Change Glow Plugs

[jasonleah1]

Hi, I.ve just followed your instructions and 3 of my plugs read the same as the battery which was 12.46v the no 2 plug gave a reading of 11.53v. due to it being 8 pm i cant get a plug until tomorrow, do you think this slight drop in voltage would cause my car to throw up the "check injection" warning light as the car pulls really well:- car is a reno megane privilage tourer 1.9dci 120. When i had the glow plug leads off, i tested the wires to the plugs and they only gave a reading of 6.23v each?? with the ignition on? Neg side of tester on neg battery, positive side of tester down the wire, i hope this is right!!! Thanks again for the post.....

[davelowe]

Hi, I.ve just followed your instructions and 3 of my plugs read the same as the battery which was 12.46v the no 2 plug gave a reading of 11.53v. due to it being 8 pm i cant get a plug until tomorrow, do you think this slight drop in voltage would cause my car to throw up the "check injection" warning light as the car pulls really well:- car is a reno megane privilage tourer 1.9dci 120. When i had the glow plug leads off, i tested the wires to the plugs and they only gave a reading of 6.23v each?? with the ignition on? Neg side of tester on neg battery, positive side of tester down the wire, i hope this is right!!! Thanks again for the post.....

The 6.23V is probably due to the fact that the regulator is expecting a load and will adjust the voltage accordingly, or the engine was warm (coolant temp sensor) and so it reduced accordingly (the plugs are not on/off devices - they operate due to various engine parameters).

I would measure the resistance of each plug - it's easier. They should be 0.6 Ohms or thereabouts.

If you get 0 Ohm or infinite - it's bust.

If they measure the stated value, you have problems elsewhere.

[jasonleah1]

changed plug today they all now show the same as the battery, This might sound a bit stupid but how do you check the resistance?? My multimeter has different measurements for ohms and i haven't a clue it starts at 200 then 2000 20k. 200k 2000k, the fault is still there, i've just disconected the battery to see if it clears the problem, I dont know what else it could be as like i said befir the car drives very very well and pulls strongly without hesitation or anything like that.

[bigstring]

At last, after 3 days of searching on https://www.renaultforums.co.uk/ I find all my answers here!

Right Im off out to change some plugs, as they have been sat there for 3 days........ also as above Number 1 cylinder looks a pain to get out, any tips?

[temp]

Brilliant post! Thank you dry_flood!

I recently had "Check Injection" message on my Renault Scenic 1,9 dci (2005). Although the engines are not the same, the post was very helpful to me.

As jamie.osborne and davet47 noted, I had a problem with a plastic cover over the injection pipes. It seems that the inlet pipe need to be dismantled in order to remove the plastic cover. So I was on my way to thank to busternlouie on his post on how to remove an inlet duct.

I managed, however, to skew the plastic a little bit, enough to check two glow plugs on the right (I'm not sure whether they are no. 3 and no.4). Lucky for me, the first was dud! I managed to replace the plug and the message disappeared!

So, I suggest checking those glow plugs first, without removing the inlet pipe. If you are "lucky", you don't have to remove the inlet pipe. But if the glow plugs near the inlet pipe are out, chances are that you have to remove inlet pipe to replace them.

Thank you all! Great forum.

[Megan1.9]

Excellent post!

My wife's car was taken to my local Renault dealership with an immobiliser problem which was preventing it starting. The dealership couldn't find anything and, as always with the car, it decided to work on it's own!!!!

Following the £50 fee just to look at the car ( ) the dealership said glow plugs 1 & 4 needed replacing at a cost of £150. I decided to do it myself as a quick Google search brought this site up and showed how easy the task was; 20 mins and £21 later and it's job done

[dean_hughes]

Just wanted to say thanks for the post, was a massive help and your tips led me right to the problem and the (low cost) fix

[paulkirky]

big bamm boom done no more service light lol best £19 and 10 min for 2 glow plugs i've done in a while.

[marty22]

I have check injecters shouting at me on the dash with no running problems so will give this a try the weekend, will update when concluded.

[marty22]

Checked this weekend all 4 glowplugs with meter as described in post and all four were reading same as batterie, and I still have check injection shouting at me, anyone got any other ideas why it may be still shouting check injection with no running problems noticed at all ?

[davelowe]

The message you have is very generic. It covers a multitude of sins, not just the plugs. Get any fault codes read.

[scottdmc88]

I changed all four plugs today, disconnected the battery for 30mins or so, check injection still popping up, what else could it be?

[Darrellinuk]

I had the 'check injection' and service light on, checked the plugs and 2 dead and 1 on its way out. Changed the 3 and the message and light still appear !!!!! Any ideas ??

[hardcore]

Is it possible to have a faulty glow plug without bringing up the check injection warning light? First start in morning for me puts out a puff of smoke from the exhaust, but after that it's fine also it starts with an awful clatter, you'd near think the engine was going to jump out.

[gwalker]

Can anyone please tell me if the ignition should be on when I test the volts. I have tried to check glow plugs with multimeter but I get a zero reading on all 4 plugs