Fault codes and poss air flow meter fault - Alfa Romeo Forum
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Fault codes and poss air flow meter fault

Hi All,

This relates to a 1999 1.8 TS 156. Flat spots, general lacklustre performance, sometimes almost a misfire. Plugged Alfadiag in and get P1172 and P1173. I set Alfadiag to give me a readout of mass air flow and air temperature then went for a drive. The mass airflow line was completely flat at the bottom of the trace throughout. The air temperature was saying 18 degrees.

As the air temperature was actually nowhere near 18 degrees (more like 8 in fact!), I'm assuming all this suggests air flow meter? It's done just over 90k so I wouldn't die of shock if it was!

Also tried logging lambda (not sure if I got the right one there seem to be loads to choose from!) but rather than the usual "square wave" I get a line pretty much running along the top of the graph with occasional small dips in it.


1. Does that seem like a reasonable diagnosis?
2. Is there a list of Alfadiag fault codes and their corresponding descriptions anywhere on the 'net?
3. How can I tell if my car is a CF2 or CF3? I've heard these terms used in conjunction with airflow meters but don't knwo what to order.
4. Is there anything else it might be?

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Re: Fault codes and poss air flow meter fault

2. Most of the codes are common, so any OBDII list would show most. But as you get into manufacturer-specific territory, finding the answers is harder and those P1172/73 codes fall into that category. Sometimes you just have to search and take a guess. VW has them as P1172 Throttle Actuation Potentiometer Sign. 2 Signal Too Low and P1173 Throttle Actuation Potentiometer Sign. 2 Signal Too High. As the older ALfa uses the VAG-COM KKL interface, they might be the same. That could be the idle actuator on the throttle body.

3. That 1.8 will be a CF2 identified by only relatively normal exhaust manifold (ie no cats) and one lambda in exhaust just before the one and only cat.

The usual way to find out if it is the lambda is to simply disconnect it and go for a drive. If it improves, it's a sign it failing and get a replacement - but only a genuine Bosch - others just don't work.

cheers, Gary

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Last edited by gazza82; 20-11-08 at 13:08.
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