Club 80-90 Forums

I’ve got a T25 Syncro with a 1.8T conversion (AGU) which seems to be running ok but out of curiosity I plugged it into my VCDS Lite which is showing several fault codes.

- Short to ground on all 4 Fuel injectors
- 16519 - oxygen (lambda) sensor B1 S1:heating circuit malfunction
- 16885 - Vehicle Speed Sensor
P0501 - 35-00 - Implausible Signal
- ABS fault (guessing that’s cos it’s removed)

After researching, this combination can be caused by the 409 fuel relay but from what I can see all the fuses & relays under the dash of the van are the original T25 ones. The only other relay I can find is in a spiders web of wires within a junction box in the engine bay. It looks like a generic relay nothing like an original Vw 409/167 relay.

I can only see one o2 sensor so maybe the codes thrown up because the others missing?!

I’m at a loss as to where the old loom starts and the new one begins…wiring isn’t my strong point. Anyone got any ideas?

Altogether the wiring isn’t great, there are several wires in the engine bay that have missing insulation so wondering whether I should just find a new conversion loom and rewire?!

Or do I just accept the codes, chuck some heat shrink over the wires and cross my fingers??

I’d put some VCDS screenshots up but I’m a newbie so don’t know how..

Thanks in advance guys

Russel Johnstone has done a few 1.8T conversions to syncro vans over the years, could be one of his, do you know anything about its history?

Are these all current faults, or are some stored? Clear them all, run it and see what comes back.

I would be surprised if it's running OK while thinking the injectors are short to ground! I would hazard a guess that there's an intermittent issue here that's worth looking closely into as this could leave you stranded.

O2 sensor heater - again, is it current or stored? This is less important than the injectors, but they may share a 12v supply that could be iffy.

Don't worry about the ABS or VSS. Ideally you would get these fault codes disabled (Easy job for anyone who does remaps), and then wire the MIL up to an LED in your cluster so that you have a functional check engine light.
Wiring up the VSS would be a bit of a faff but could improve driveability at low speeds, and make a very slight improvement to fuel economy by allowing the ECU to completely cut off the fuel on overrun.

Thanks for taking the time to reply both!

I think the previous owner mentioned that MV Engineering in Telford did the conversion although another guy finished it off. Not sure who or what the story is there.. not sure if MV are still trading

I’ve cleared the faults and run the van for 15 mins idling (got a brake problem I’m trying to sort so can’t take it for a run yet). The injector faults haven’t reappeared (yet) just the ABS, VSS and o2 sensor. Not sure if the injector faults would show straight away, I’ll keep my eye out.

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There are some, late of this parish, who may have something to say when MV Engineering is mentioned.

If the ECU did think the injectors were currently short circuit, it'd show up straight away and the engine wouldn't run.
For it to have tagged them all as short circuit, I'd suspect an issue with the common positive supply to them (they have the earth switched on and off by the ECU, and the positive is on an ignition switched feed from a relay)

I would personally spend a bit of time familiarising yourself with where the engine ECU and injectors are is supplied with 12v and ground, You might find something that needs attention, but in any case you'll know your way round it a bit better if the fault does reappear and it leaves you stranded.

here are some, late of this parish, who may have something to say when MV Engineering is mentioned

…sounds intriguing, I’m praying it’s nothing to do with standard of workmanship?!

Thanks cobblers, makes sense. I’m definitely keen to get to know the van a bit better! Might be invaluable when stuck on the side of a road somewhere!

One other thing I need to sort is the tacho, don’t currently have one on the standard clocks so might just add an aftermarket one, any idea where to take the signal from? I was hoping to use one of the OBD ones but my AGU doesn’t support OBD

There will be an output pin from the engine ECU to drive a tacho. To save running a wire all the way down the van, use the OE tacho wire which should emerge in your engine bay junction box. Green wire, running to pin 9 on the plug for your clocks.

1.8T should have a OBD-II socket, its well into that era for VAG engines. Unless its been pruned off the harness.

AGU is the cable throttle 150PS single narrow-band lambda engine, late 90's into naughties i.e. the obvious one to swap back in the day before convertors got to grips with fly by wire throttles.

Inclined to cook their oil and sludge up the sump because the turbo is oil cooled not oil and watercooled iirc but otherwise a great engine, I have the NA version in our old avant B5 and it does like to rev!

silverbullet wrote: ↑01 May 2025, 12:38 1.8T should have a OBD-II socket, its well into that era for VAG engines.

They have the 16 pin socket, but the early ones use K line for diagnostics comms and don't have CANbus, which is what the OBDII gauges generally use.

E D I T: They may actually have CAN - Pins 58 and 60 of the ECU on a bosch ME7.5 are usually CANL and CANH. Might not be broadcasting anthing on there, though. And maybe this is an ME7 not a 7.5

https://www.scribd.com/document/3932218 ... AUM-Pinout

They have the 16 pin socket, but the early ones use K line for diagnostics comms and don't have CANbus, which is what the OBDII gauges generally use.

Yes, exactly this. It’s got the socket but doesn’t support OBDII, compatibility doesn’t show up when tested with VCDS. Bit annoying to be honest.

Not sure if it’s a ME7 or ME7.5…how would I know?

Thanks silverbullet, it does go well but not well enough to mangle the gearbox want to get a tacho sorted so I’ve got some idea what revs I’m doing. Think it’s geared for a diesel so feel sometimes like I’m labouring the AGU a bit and asking it to pull from too lowdown in the rev range.

This is the van by the way in case anyone recognises it..

Vaughanylive wrote: ↑01 May 2025, 13:58 it’s geared for a diesel so feel sometimes like I’m labouring the AGU a bit and asking it to pull from too lowdown in the rev range.

I think that's a Syncro on big tyres thing, my 2.1 wbx is the same. I find myself having to consciously hold onto each gear for 6 or 700rpm past where the natural change point feels, otherwise the next gear lands just that bit too low in the rev range for comfort. I think it's a combination of 4 speeds spreading the gears out a little too wide and the increased rolling radius of the bigger wheels accentuating this

Defo a big tyres and only 4 gears thing. The engine should make 210 Nm in 150PS spec which is 40 more torques than a box fresh DJ, assuming it hasn't had a cheeky remap. The transmission is ok for 250Nm if you don't drive it like you stole it or try to tow a 2T trailer up a 1 in 4 whilst fully laden in 50 degree heat.

The van does look familiar, can't place it.

Pulled from Wikipedia:
 1.8 R4 20vT (EA113/EA827)
identificationparts code prefix: 058, 06A, 06Bengine displacement & engine configuration1,781 cc (108.7 cu in) inline-four engine (R4/I4); bore x stroke: 81.0 mm × 86.4 mm (3.19 in × 3.40 in), stroke ratio: 0.94:1 – undersquare/long-stroke, 445.2 cc per cylinder, compression ratio: 9.0–9.5:1cylinder block & crankcasegrey cast iron; five main bearings, die-forged steel crankshaft, fracture-split forged steel connecting rods, Mahle forged aluminium alloy pistonscylinder head & valvetraincast aluminium alloy; five valves per cylinder, 20 valves total, hydraulic bucket tappets, timing belt-driven double overhead camshaft (DOHC) with variable inlet valve timingaspirationcast aluminium alloy intake manifold, turbocharger, intercoolerfuel system, ignition system & engine managementmulti-point electronic sequential indirect fuel injection with four intake manifold-sited fuel injectors; mapped direct ignition with four individual direct-acting single spark coils; Bosch Motronic ME 7.5 (MBE 975F on Industrial variants) electronic engine control unit (ECU), red line: 6,500 rpm, rev limit 6,800 rpmMass
149 kg ('BAM' engine, dry)
DIN-rated motive power & torque outputs, ID codes, applications110 kW (150 PS; 148 bhp) at 5,800 rpm; 210 N⋅m (155 lbf⋅ft) at 1,750–4,600 rpm — AEB, AGU