156 JTS 2.0L engine light staying on

[bonno]

Hi Alfisti
I would like to share my recent experience involving Engine Light staying on with my 156 JTS. It occurred not long after filling with Premium 98 and involved a slight smell of petrol fumes within the cab. On close inspection, it was discovered that the petrol cap was not fully engaged in the closed position, thus resulting in escape of petrol fumes. Did the disconnect battery terminal procedure to clear engine light but with no success. Ended up purchasing diagnostic scanner from e-bay and when connected to the cars OBDII socket and run thru the check cycle revealed P0430 fault code. A cross reference on User manual indicated that Catalyst Efficiency below threshold (bank 2). Cleared code via diagnostic tool and presto Engine Light had gone after start up. Went for a drive and the Engine Light did not come back on. Hopefully, it was just the fuel cap engagement, but if the fault reoccurs it might be necessary to investigate further. Have included 3 photos - photo 1 location of OBDII socket, photo 2 Error code P0430 displayed and photo 3 Manual extract code reference .

[Citroënbender]

Do the JTS models have a microswitch on the fuel cap?

Have seen similar on common rail diesels as part of the additive metering calculation but never encountered it on a petrol engine (yet).

[bazzbazz]

No, They don't.

[bonno]

Checked the operators handbook involving fuel cap and if faulty will effect petrol vapour recovery system and this may have triggered the code. PS no mention/detail of microswitch incorporated in fuel cap. 

[bonno]

Further to my earlier post I have attached 2 x links that details canister purge that may have attributed to the Engine light coming on and resulting in P0430 error code.
http://p0430-alfa-romeo.autotroublecode.com/
https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-canister-purge-solenoid
cheers
bonno

[psproule]

Catalyst efficiency faults are usually because the thermostat is gone and the motor is running too cold. It then runs too rich and triggers occasional catalyst faults. What temp does it sit at?

Pat

[bonno]

Hi Pat
The temperature gauge sits on quarter (light traffic) and half (city traffic).

[Citroënbender]

That doesn't sound ideal. A properly working thermostat should give a constant temperature reading under normal operation, you would only expect lower if in Arctic cold, or higher if towing a heavy load on a warm day.

[poohbah]

Definitely sounds like the thermostat has gone (or is on the way out) if its at quarter temp on gauge on highway running but goes back to normal in city traffic.

[bonno]

Thanks Guys
I also found it a bit strange with respect to temperature variation between heavy traffic and highway cycle. This suggest that the thermostat is stuck open (partially/fully), thus not achieving normal operating temperature on start up, which I will  address at the next available opportunity. I am still not convinced that a faulty solenoid controlling canister purge was not the culprit, because it is too coincidental of the smell and refuelling the car when the engine light appeared.

[poohbah]

I'm sure I read somewhere that damage to the cats from extended "cool running" was one of the potential problems that could eventually result if a failed thermostat was left in place for too long.

Though I imagine it would take a long long time for it to do that.

[bonno]

Poohbah you have read my mind again. Checked pricing on e-bay for a replacement thermostat unit at a modest price of under $100 including delivery (refer to link).
http://www.ebay.com.au/itm/Alfa-Romeo-Thermostat-2-0-JTS-156-GT-GTV-Spider/263150845861?hash=item3d45033fa5:g:9JYAAOSwuxFYzLMq

[Citroënbender]

OEM are Behr brand, I have also fitted Vernet without a problem. They and Facet ones look awfully similar out of the packet.

Strongly recommend a set of "Clic Clip" pliers, these will allow easy reuse of the air trunking clips, and also the smaller hose clips on the thermostat.  The large one is probably best replaced with a worm drive clamp unless you can borrow a factory style tool. 

[poohbah]

I'm sure I read somewhere

In fact, I only had to look as far as Pat's post a few before mine!