Hi all. 

 

First time poster here but used this forum for many a fix on my 2006 1.9 TDI PD100. 

 

I had the P0118 code and EML on, so replaced the coolant temperature sensor. The code and EML keep coming back after a reset. 

 

I've read that this can be a wiring issue, so I've checked as much as I can physically and all looks OK. Does anyone have any pictures of usual areas they may chafe or become damaged? Also I've seen to measure from the plug to ECU - is that on the connector to the ECU itself? Any help would be much appreciated as MOT is up on Saturday and I have no money to get this sorted by someone else beforehand. 

 

Thanks!

16 minutes ago, Ozakki87 said:

measure from the plug to ECU - is that on the connector to the ECU itself?

Yep.

Pin 1 of the sensor connector goes via a blue wire to pin 112 on the ECU connector, pin 2 at the sensor connector via brown wire to pin 104 at ECU.

Look for signs of fluid inside the connector housings at both ends, as well as any sign of dirty or corroded contacts.

 

I know you'll want to fix it regardless, but it shouldn't actually be a problem at MOT if the light stays on. Note the last sentence here, your car is too old to have the MOT test care about the MIL status:

Engine malfunction indicator lamp (engine management light or ‘EML’)

Turn on the ignition and check that the engine malfunction indicator lamp (MIL) illuminates and then goes off. On some vehicles it will be necessary to start the engine before the MIL goes off.

You need to inspect MIL fitted to diesel vehicles with 4 or more wheels and first used on or after 1 July 2008.

 

From here: 8. Nuisance - MOT inspection manual: cars and passenger vehicles - Guidance - GOV.UK (www.gov.uk)

Brilliant, thanks for the information. Blowing a gale and torrential rain here so will check those connections when it calms down. 

 

I'm thinking that I got coolant in the connector when replacing it at the sensor end - wonder if that's caused an issue? And if so, not sure how best to clean them? WD40?

Tried WD40 on the connector but no joy. Sorry for being dense, but is it these connectors I'm meant to be checking as I don't see the pins numbered?

Yeah,  I'll get you a screenshot of pin layout.

Was the sensor end connector moist inside?  

Yes that's the ECU main connector, the pins are not numbered so you'll have to count how many pins in a row times rows to find pin 104, the first and last pins might be numbered to tell you what order they're in.

Edited 6 October, 20214 yr by sepulchrave

Thanks both, much appreciated. Abandoning the car at work and will look tomorrow. Sensor end was moist from coolant I spilled in it. Squirted with WD40 and left to dry but no luck. They don't really look that corroded in any way though. 

Hopefully this helps, double-check if poss with any tiny printed numbers on the plastic.

 

Ok so I've had chance to look and I've got no continuity between pin 2 and 104 on the ECU connector. What's the thing to do with this? Change the loom?

Run a separate wire between accessible parts of the existing wire to prove the fault goes away when you splice that in.

Then decide whether you care about appearance. 

1 hour ago, Ozakki87 said:

Ok so I've had chance to look and I've got no continuity between pin 2 and 104 on the ECU connector. What's the thing to do with this? Change the loom?

 New engine looms are available still from TPS but they are circa £500, used ones obviously a lot cheaper but how reliable the used loom will be - who knows?

Oh dear, looks like the car is a scrapper then. I've been looking at replacement connectors to splice in in the hope it's the sensor connector end that's at fault. Even tempted to knick the wire to expose the conductor to test from the ECU plug. 

 

SUTOMOTIV Part Number 1J0973702 2 Pin Female Connector Wired Plug Socket Harness Repair Wire AD042 https://www.amazon.co.uk/dp/B08P9HWD6Q/ref=cm_sw_r_awdo_navT_g_VWR0MTKB979FXFP053MN?psc=1

11 minutes ago, Ozakki87 said:

Oh dear, looks like the car is a scrapper then.

Drastic action considering I've already explained that it shouldn't fail MOT! (Unless the default map with no coolant temp input makes it too sooty for the emissions).

 

I reckon there's a strong chance the wire is bust near the engine, but check the loom for scuff damage wherever possible, and yes, don't be shy of exposing copper at either end of the wiring to help with pinpointing the fault location, or having said that, poking a pin/needle through the insulation to minimise damage while allowing probe connection to said item.

Edited 7 October, 20214 yr by Wino

24 minutes ago, Ozakki87 said:

Oh dear, looks like the car is a scrapper then. I've been looking at replacement connectors to splice in in the hope it's the sensor connector end that's at fault. Even tempted to knick the wire to expose the conductor to test from the ECU plug. 

 

SUTOMOTIV Part Number 1J0973702 2 Pin Female Connector Wired Plug Socket Harness Repair Wire AD042 https://www.amazon.co.uk/dp/B08P9HWD6Q/ref=cm_sw_r_awdo_navT_g_VWR0MTKB979FXFP053MN?psc=1

 

5 hours ago, Wino said:

Run a separate wire between accessible parts of the existing wire to prove the fault goes away when you splice that in.

Then decide whether you care about appearance. 

 

@Wino already gave you the correct answer, you can just snip the dead wire at the ECU end and the sensor end and run a new length of wire between them using crimp connectors or better yet, solder and heatshrink.

Half an hours work and a few pennies then just zip tie that new wire tidily and it's fixed.

Might sound drastic but this is an extremely battered example with 200k miles. Definitely needs new rear discs and pads as well as whatever else they pick up on. Too much of an unknown on what is now a pretty worthless car! I'll try belling the cable out before it goes to the sensor connector.