w.ashcroft

Hello,
I have a fault on my car which I am struggling to get rid of, critically it is preventing the DPF from regenerating:

4030

Which seems to mean one of these things depending on DDE version:

EGT (exhaust gas temperature) Before Cat - Open Circuit or Short Circuit to B+
Exhaust Backpressure Sensor Before Particulate Filter - Signal

(Note how the DIS screenshots report this fault as the backpressure sensor, but the test schedule wants to test the temperature sensor for it)

In any case, this fault is definitely caused by the "exhaust gas temperature sensor before cat". As you can see from my DIS temperature readings, this one which shows simply as "Exhaust-gas temperature" is reading 259 degrees (the car was cold).

Now, this seems simple, replace the sensor (I believe its the sensor closest to the front of the car on the DPF). However, I have checked the resistance across the sensors connector pins, 16.96k Ω, and this is similar to the resistance across the other temperature sensor (further back on the DPF) at 18.4k Ω.

To verify the connections and wiring, I tested the resistance at the DDE connector (pins 8 and 58 for this front sensor, pins 9 and 34 for the other back sensor) - the resistance is exactly the same as measured at the sensors.

Are these plausible resistance tests an indicator the sensor isn't faulty, in which case what else could be causing error code 4030 and the 259 degree temperature reading?

Cheers,
Warren

w.ashcroft

Hello,
I have now resolved this fault, just before it was about to beat me...

Everything was pointing at a costly DDE fault, the sensor was fine, the wiring was fine, I'd even flashed the DDE software, but the fault persisted. I started to look at and test the DDE side.

These sensors are simply a two wire resistor/thermistor circuit, the ECU sends 5v through them and using a voltage divider can measure the voltage change in the circuit as the resistance (temperature) in the sensor changes.

Firstly, the error descriptions given by DIS don't match up and should be ignored, there is also confusion whether "before" means before filter, engine side or before filter, exhaust side. I was able to work out 4030 is the error for a disconnected sensor, the sensor closest to the front of the car on the DPF (TS_KAT - pins 8 and 58 on the DDE). Whereas error 4020 would be the sensor further back on the DPF (TS_CSF - pins 9 and 34 on the DDE). I didn't have 4020 so I knew this further back sensor and circuit was good.

Checking the TS_CSF sensor, I had 5v across the connector, but checking the TS_KAT sensor connector I had 0v. This a DDE fault, it wasn't supplying 5v or ground to this connector (I'd already verified the connector/wiring, see above).

Further testing allowed me to determine the crucial 5v signal was infact being supplied, it just wasn't supplying ground. As soon as I removed my ground probe from the connector to the chassis I had 5v on the TA_KAT sensor connector.

Luckily this is an easy fix, at the DDE end of the wiring loom I tapped the wires for both pins 8 and 9 together (both sensor grounds) to give me the ground I needed at the sensor connector. Now both sensor connectors had their functional 5v circuits.

I now had no faults whatsoever on the DDE and as soon as I got on the motorway my DPF regeneration kicked in, putting an end to hours of troubleshooting my DPF not regenerating and money unnecessarily spent on replacement sensors etc...

More info about my DPF regeneration troubleshooting here:

https://5series.net/forums/e60-discu...rating-143340/

I hope this helps somebody somewhere.

ripley

So what happened to the ground?

Can you determine what caused this problem in the first place?

Stephen York

Hi, I know this is an old thread, but I'm having the same problem.
Diesel is mixing my oil as the car isnt going through the regen process.
Code 4030 wont clear, and even when my car is cold the exhaust temp is still reading 259oc