Hyundai i30 Issues

bjones371

OK - the trader got the part from a dealer but haven't been able to get a garage to fit it until Monday, which is a PITA on its own...

They've left the part with me so I can go straight to them with it, but the part they've bought is an exhaust temperature sensor. They've convinced its the right thing - but I've seen exhaust pressure sensors on ebay and at breakers and they look nothing like the part they've just given me.

Have they ordered the wrong thing? [emoji848]

Chris Muriel

See if you can tell by looking here (there are several exhaust pressure sensors on the web page) HYUNDAI I30 Car Parts at GSF

Also pics of i30 exhaust gas temperature  sensors here : 3922027450 Exhaust Temperature Sensor for Hyundai I30 2007-2009 | eBay

bjones371

Yep, so the exhaust gas temp sensor looks like the ones in the second link, and the exhaust pressure sensor that I've found in the engine bay looks like the sample pic on GSF, although they don't stock the exact right model.

I had another play today - if I clear the codes and do a couple of motorway runs I get P0472 and P2002 codes logged again. So I cleared the codes, then disconnected the exhaust pressure sensor from the wiring loom, didn't drive the car anywhere, and that immediately gave me P0473 as a pending code, so disconnecting the sensor altogether does give me a different code.

Apparently another possibility is that the rubber hoses that connect to the sensor could be blocked... So disconnecting those and checking them for blockages is tomorrow's thing to try. It is going to another garage I've been sent to by the trader first though to see what they make of it.

I'll keep you all posted

bjones371

Exhaust temperature sensor replaced - fault still present checked that the hoses are free of splits and blockages, and done some checks on the wiring for any shorts or open circuits, so I'm thinking the differential pressure sensor may be faulty. Unfortunately, a replacement is dealer only, and costs a lovely £300!

The PN for the sensor is 392102A750. But at some point in the car's production life cycle they changed the sensor for PN 392102A800. The part ending 800 is much easier to get hold of, and much cheaper as well. I know nobody can say categorically, but what are the chances of the differences just bring visual, and the internals being exactly the same? Or, if I were to pick one up and connect it to the car, and there are differences, it would probably just throw a check engine light like the faulty one is anyway wouldn't it?

car-man

I wouldn't have expected the problem to be a temp sensor.
Differential pressure sensor was my thinking.
The 800 part number could be a superseded part, in other words they made a different sensor and dropped the other one.
Faults like this one are a pain to sort out as the parts are so expensive if you get the wrong part!

bjones371

Yeah I think they ordered the wrong part - so I'm giving up with the trader for now to be honest, sinking a lot of time and effort into getting the car to and from garages, and not really getting anywhere. They sank £110 into the temp sensor as well.

I can get the 800 version for £24, so I think at less than 10% of the price it's worth the risk of getting one, connecting it up to the harness and seeing what happens. The fault is being logged at ignition on rather than engine start, so I'll be able to see how the ECU responds to the sensor without starting the engine up.

bjones371

Spent some time with a multimeter today, the central pin of the harness that plugs in to the sensor reads 5.68V when the harness is disconnected. When I connect it and back probe that pin, the voltage is 1.01V. I disconnected the exhaust hoses and still got 1.01V, no fluctuations at all.

According to manuals/spec sheets, a reading of 1V means equal pressure on both inlets. Since the DPF is unlikely to be completely clean (the car has done 115,000 miles) that sounds like it probably will be a fault with that pressure sensor?

bjones371

I'm back

I've done some more playing with a more accurate multimeter and the values do change by ~0.006V when the hoses are disconnected so the sensor is reading change correctly, which is a start!

What I did find was that when I applied pressure to the harness in a certain direction, the voltage would drop to ~0.232, and stay there until I reseated/rewiggled it back. Again this was measured by back probing at the sensor end not the ECU end, ruling out wiring issues, continuity from the crimped connectors in the harness back to the ECU checked again to be 100% sure though, and I wiggled the wiring trying to find a break but couldn't.

So, are there any ideas what I could do to diagnose next? Could it be some kind of issue internally in the sensor that causes the voltage to drop in that manner when pressure is applied - or maybe a problem with the crimped connections on the  5V supply or GND that causes that connection to break when pressure/movement goes in a certain direction, and that makes the output voltage drop?

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