Fault code readers

[rvr]

MG TF 2005. I got this car in with a rough running condition, no codes present. I was shown an Autel 801 (I think) connected to the dlc showing no current or pending codes.  To look at live data I connected up an ACR4 and it showed 4 codes. I am confident that these codes were present – I am certain that 2 were valid. The car is sorted and gone; however the code reader issue got me thinking!

Before the car left I tried a number on cheap code readers, those that connected showed no codes present. Those that could,were able to read the vin no. and live data.

Is there any way to be sure that a diagnostic machine is reading the ecu?

[Karl]

Yes !


Use some professional equipment

No universal handheld scan device will cover all makes and models

Some offer better coverage on certain makes than others etc..

The theory is they should all pick up generic codes, but this is definitely not the case.



Most garages need to invest in several machines to cover a wide range of cars


I think the autel md801 is more for diy use



You also need to access all vehicle systems to get a clear picture of what's going on, not just PCM

[natedog]

I've got an autel maxscan vag version, and a launch cr6. They both have cars that they won't extract codes from, despite claiming to be able to

[Stilo]

I too found out that cheapie scanners are really for DIY use. For example, you'd think that a common make like Ford would be well covered by virtue of their popularity, but getting manufacturer specific and pending fault codes that don't put the MIL on require the sort of high-end professional scan tools that KarlB speaks of.

Likewise with a Grande Punto I had a while back and I disconnected the EGR valve to try trace a running fault. No MIL on, and a generic scanner showed no codes either. Plugged in a Fiat-specific scan tool and every code under sun came back!.

Moral of the story: cheapie scan tools are cheap for a reason - they can't always be trusted.

[valhalla]

Mar 27, 2015 14:51:47 GMT 1 Stilo said:

Moral of the story: cheapie scan tools are cheap for a reason - they can't always be trusted.

Especially with MG Rover, very much off the beaten track with its diagnostic requirements. I only know one tool that will read the MG ZS & ZT (45 & 75) ABS after 2004, and that's Rover's T4/T4Mobile - unless anyone can enlighten me to a better way?

[rhyds]

Rover diagnostics are absolutely shocking if you don't have a T4.

For example, in 2000 the 25 and 45 models got new MEMS3 engine management. Now, apparently, it's written in the factory service manual that the EML will come on with the ignition, go off when the engine starts but will not light under ANY other circumstances!

The other fun bit is that despite the MEMS3 system being capable of EOBD, it isn't actually activated on any ECU before 2002 (when it became an EU requirement). I've heard stories of some owners, unable to find anyone with a T4 locally, fitting a matched post 2002 ECU/immobiliser to get at least some kind of fault codes to read.

[Monkey]

I'm glad I only with Ford, I feel for garages trying to diagnose and fix anything that comes through the door!

You'll never have enough scan tools!

[Deleted]

The trade aren't bothered about rover vehicles anymore ,too old to spend on ,only specialists and they will have the kit for these anyway, diy lol

[valhalla]

Mar 28, 2015 8:54:42 GMT 1 rhyds said:

Rover diagnostics are absolutely shocking if you don't have a T4.

They're not a heap of fun if you do have a T4. As befits any of the "factory" systems, Testbook is bloated, slow, and aimed painfully at the dealerships. The relief of being able to use a general-purpose toolset that can do the same job (AutoCom CDP+ is one that comes to mind) is huge. Unlike VW dealerships (that I know sneak in VCDS whenever they need to get the job done), the Rover and Landrover guys never had the choice.