I know this has been asked / answered many times but just want to check before I commit to an reasonably expensive part, as I don't have access to a diagnostic locally (within 10 miles) or for less than £35 a go.

2001 1.4 MPi AQW 8 valve has started giving the following symptoms when warmed up (haven'y noticed at all when cold) 1. Lights dim and brighten, not a rapid flicker but more like power supply is fluctuating, 2. it is usually but not always accompanied by a high pitched beep from the engine bay, sometimes a short beep and other times a longer beeeeep not too loud but definitely noticeable and 3. the power assist on the steering seems to drop in and out at the same time, for intermittent bursts of a second or two and for maybe 10 seconds duration total. When the lights stop dimming etc so do all the other symptoms.

The car has had a new alternator and belt ( tension is fine) within the past 4 months and output is fine at idle and at 2000 ish revs.

I suspect the steering angle sensor but don't want to jump straight into that without other opinions.

Any help appreciated

I'd start with testing the alternator if I were you, it sounds like your voltage is dropping too low to run the PAS.

Agreed.

 

And if you do get into fault codes, take note that an "implausible value" narrative for a sensor is an indication that the sensor is returning rubbish values but within the allowed range.

Thanks both, I will get the alternator checked by a specialist as I have done all I can checking the output.

Have you checked this?

https://www.briskoda.net/forums/topic/401778-battery-light-and-associated-problems/