Here's a curious thing...

Tenesmus · 23rd January 2019, 20:59

So the car started lumpy idling before Christmas. I went to the garage, they speculated coil pack but plugged in and the fault codes were VIS motor(s) so I started thinking about an inlet manifold.

I put up with it but it deteriorated and then last week it seemed to be misfiring and lit up the check engine light. I assumed this was a symptom of the manifold problem and brought it to the garage for them to fit a manifold and motors they took off a car.

But first, they plugged in again and it returned a misfire code. So they fitted a coil pack, and that sorted it, no more fault codes. So the chap was right in the first place. And it was much cheaper...

Anyone else come across misleading fault codes? They said they had noticed some recently on cars brought in.

trikey · 23rd January 2019, 21:02

The manifold won't throw up an engine light, glad your sorted now

SCP440 · 23rd January 2019, 21:46

A low battery on a modern car can through up false codes, the other part that can give problems are if you have a diode going down in the alternator it can cause spikes and I have seen that give codes but never for the charging system.

23rd January 2019, 20:59	#1
Tenesmus Loves to post Rover 75 Tourer Join Date: Nov 2014 Location: Penzance Posts: 481 Thanks: 17 Thanked 69 Times in 52 Posts	Here's a curious thing... So the car started lumpy idling before Christmas. I went to the garage, they speculated coil pack but plugged in and the fault codes were VIS motor(s) so I started thinking about an inlet manifold. I put up with it but it deteriorated and then last week it seemed to be misfiring and lit up the check engine light. I assumed this was a symptom of the manifold problem and brought it to the garage for them to fit a manifold and motors they took off a car. But first, they plugged in again and it returned a misfire code. So they fitted a coil pack, and that sorted it, no more fault codes. So the chap was right in the first place. And it was much cheaper... Anyone else come across misleading fault codes? They said they had noticed some recently on cars brought in. __________________ 2005 Connoisseur 2.5 auto SE Tourer in BRG with Sandstone Beige and Black piping interior (the 2nd of only 7 Rover 75s produced 5th November 2004, and it’s the 244th of 303 facelift British Racing Green 75 tourers built worldwide). All I've done is add Rover walnut gear knob and handbrake... 2016 Vauxhall Viva SL (Father Jack) "assisted manual" (auto) in purple. Going rusty underneath already... Last edited by Tenesmus; 23rd January 2019 at 21:00.. Reason: tidy up formatting

23rd January 2019, 21:02	#2
trikey Premium Trader Rover 75 Join Date: Nov 2010 Location: Devon Posts: 33,760 Thanks: 8,837 Thanked 14,831 Times in 8,030 Posts	The manifold won't throw up an engine light, glad your sorted now __________________ Lest we forget..

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23rd January 2019, 21:46	#3
SCP440 I really should get out more....... MG ZT-T 260 Join Date: Feb 2016 Location: Witney Posts: 2,504 Thanks: 6 Thanked 910 Times in 571 Posts	A low battery on a modern car can through up false codes, the other part that can give problems are if you have a diode going down in the alternator it can cause spikes and I have seen that give codes but never for the charging system.