I'm new to Volvos and managed to acquire a 2004 S40 T4 here in the Philippines.

I got the car fairly cheap because of some issues that the former owner (also a newbie) said he wasn't able to resolve.

The Check Engine Light (CEL) and Traction Control warning lights were always lit. I noticed that the idling wasn't very steady and when accelerating it felt like it lacked power, and i didn't really hear the nice sound you get from a turbo. Also after driving hard and fast for a few minutes, the engine wold lose idle and cut off. It will restart but cut off immediately. You'd need to cool down the engine first before it will start and hold idle.

I brought it to a shop to check on the errors and found a few:

1. MAF Sensor
2. Torque reduction
3. Camshaft Reset Valve

An intermittent Aircon error would come up and that seemed to have something to do with the Aircon switch, which malfunctioned intermittently. Decided to hold off on that as it wasn't the most important repair.

The auxiliary fan would also keep running for 10 minutes even after engine was shut - this would drain my battery all the time. We replaced the thermostat and some relays and that seemed to have solved that particular problem. The camshaft reset valve was also replaced and that error didn't show up anymore. The torque reduction issue, i was told, can be resolved last as the MAF issue was more important.

To resolve the rough idling and lack of power issues, we replaced spark plugs, cleaned and eventually replaced IACV, cleaned the throttle body. Performance improved but it would still cut off when hot and would be hard to start and wont idle if it does.

MAF and Traction Control errors still present. Tried replacing the MAF a number of times but problem was still there. Then we noticed in the scanner that there didn't seem to be any power going into the MAF at all - i thought that this could be the problem, but what could be the cause? Checked the wiring and it seemed okay, no frayed or cut wires.

Is this a common issue? Would this affect the function of the turbo? could it be a ECM issue?

Expert thoughts and advice would be greatly appreciated. Thanks!

 

you need to have all the codes read including chassis codes and powertrain codes. Typically a traction control warning points to either a faulty wheel sensor/speed sensor but can also point to the ABS controller board (which can develop cracks in the solder joints). The ABS controller can be replaced without opening the brake system as it bolts onto the ABS pump. Generally ECMs don't fail but an easy thing to do is to pull out computer, clean the contacts with electronics cleaner and reinstall (disconnect the battery and discharge the system first). I'd also consider replacing the engine coolant temp sensor as that may cause the fan run on and can possibly give a false code -
such as blaming the MAF.

 

Hi@mt6127 - Thanks for the advice. The fan issue has been resolved by replacing the fan altogether. The bigger issue is the MAF error. There is no power that goes into the MAF.

 

Check the fuses especially the under hood fuses and relays.

 

Yes, i've checked and cleaned them all. Still the same.