Hi to all, 2003 XC70 station wagon, AWD, 2.5T, 217,333 miles. Several replacements done, then I bought the car after enough road testing to satisfy the mechanic the problem had been fixed. Yesterday (Monday, Jan 30), cruising at about 75mph, going uphill with cruise control on, car went into Reduced Engine Performance mode. Here's a list of what has been replaced / tested prior to this fault happening:

accelerator position sensor
engine speed (crank angle) sensor
mass air flow sensor
boost pressure sensor
vacuum hoses between intake manifold and brake booster
checked calibration of turbo boost pressure - okay with room to spare
installed a known good boost pressure control valve
cleaned PCV, checked for restriction, passed
new plugs

Mechanic repeatedly got code ECM-981A (internal fault) using VIDA software. ECM, and wiring between the ECM and ETM, had been replaced prior to yesterday's fault.

Mechanic is considering replacing the ABS module, since the speed signal comes through the module to the speedometer. I'm also having the mechanic send out the dashboard instruments for reconditioning, because the clock intermittently scrolls backwards fast, and I can't switch between the T1 and T2 trip odometers.

Thoughts / comments / suggestions? Thank you very much

 

check in with Xemodex - they have diagnostic flow charts for both ETM and ABS module faults as well as common symptoms. Both are prone to failure for your year.

 

Hi, just wanted to share that the reduced engine performance (REP) problem on this 2003 XC70 has been fixed. The dashboard instruments had been acting weirdly. The clock on the RPM instrument would erratically scroll backwards fast, and I couldn't select between the T1 and T2 trip odometers on the speedometer instrument. Also, I would push in the selector pin, and the odometer would reset, and then revert back to its original value and continue tracking mileage. The fix was to remove these two instruments and send them to xemodex for reconditioning. Actually, they just replaced the units, and the mechanic sent in the old ones as a core charge. Plus, there were two spurious tones, one that sounded about 30 sec after startup, and one that sounded about two minutes after startup. No clue what these tones were, or what caused them.

Now, the clock tracks time as it should. I can select either of the the two trip odometers. And no tones sound on startup. Best of all, there is no REP mode activated. After the repair, I went looking for it, going up long hills in cruise control. Nope, no activation. Rock solid. So, it may have been that the speed signal was going the speedometer to the ECM, and the fault in the trip odometers was scrambling the speed signal input tot he ECM somehow. Not sure, this is just my theory. But it's been two days of driving tests, placing the car in conditions in which the REP mode would activate, and it has not.

 

Hello again - I lied. After reconditioning the dashboard instruments, the car once again went into REP mode, while going uphill and while in cruise control. The hill was very slight but it was an upward grade. I was going about 78mph, and added some gas to get past a few trucks, and that's when it went into REP mode. I put the car in neutral, shut it off, turned it back on and started the engine, then put it in drive. Ran fine after that. But I'm disappointed after the fix above, thought that did it.