Glow plug light flashing

[AdamLa]

Hello,

I have a flashing glow plug question - Audi A4 2015 Reg. 

The problem initially started on a very cold morning. I was late for work so put the key in and drove off immediately. The flashing glow plug light came on and the car went into limp mode as I tried to accelerate. I stopped a few minutes later, re started the engine and the glow plug light didn't illuminate again. 

I've had this problem a while now though. Every time I start the engine, and drive off, after a few minutes the glow plug light will begin to flash. I then stop the car after a few more minutes of driving, switch the engine off, and back on again and the glow plug light does not start flashing again once I start driving.

If I allow the car to idle for 10 minutes after initial start, so that the temperature has started to rise, the glow plug light does not flash when I start driving. 

If I switch the engine off and park up for up to 4 hours or so, on re start (after a few minutes of driving) I do not get the glow plug light flashing. If I park up for 8 hours or more, I have the glow plug flashing light issue again. 

I took it to the garage but the mechanic was stumped. Codes checked - I don't have the actual codes but he said he cleared "oil pressure" and "pressure sensor cylinder 3 (circuit malfunction". He also checked the glow plugs themselves which were working fine. 

The glow plug lights up when you put the key in and extinguishes as expected. When the car is started, the glow plug light does not flash or illuminate. It only ever flashes after a few minutes of driving. 

Any ideas? 

 

[AdamLa]

Just had the AA out to have a look. The scan came up with error code P164B00 - Oil Pressure Switch Malfunction. He cleared the faults, I took it for a drive and sure enough the glow plug light started flashing again. Re scanned with the same error code. 

He suggested getting the battery changed. I've had the car for 4+ years and never changed it. Lots of auto stop start in London. Auto stop start currently disabled (says malfunction) since this glow plug light has been flashing. He tested the battery - measures 12V but as soon as headlights were put on it significantly dropped. 

He was more useful than the garage / mechanic.

[Steve Q]

Glad the aa have helped. If it's not the battery then I guess the switch is the next port of call 

[MinhaalN]

Hi AdamLa,

I am having the same exact issue as you've described on my A3 2017.

Car has never gone into limp mode though, I've been on the motorway at normal speeds with the light flashing the entire journey. But as you've described, car turned off at work and restarted 4+ hours later on the way back from work - doesnt illuminate.

Next morning it does illuminate again.

Although heavy acceleration always seems to bring it up whatever the conditions. 

Fault code is Oil Pressure Switch related.

Did you manage to fix the problem and what did you need to do? Was it simply changing the switch?

Please please tell me it was an easy fix 😁