codes: 4131 & 1212.

'95 2.7: I had a 1-4 CEL before I put her away for the winter. Her last major was 2 years ago
Took her out a couple days ago and it was CEL free for a couple miles. Then CEL came on.
pulling the codes, 4131 & 1212.
I checked connections, purged the codes with a reset.
CEL came back blinking as described by others...comes on within 1/2 mile with constant speed (25mph in my case) and if I stop for a stop sign or speed bump, it goes off for 30secs to a min then comes back on.
sometimes it goes off by itself. It's almost as if its following a cycle.
But I no longer get a code from the ECU
I checked the 2ndary air pump - seems fine. if there were a problem with it, I'd expect CEL 5-8 too.
anyway, cleaned the MAFs - no difference. swapped them- still CEL 1-4
Last time for me it was a voltage issue - checked - it's fine between 12-14V
The car seems to run OK. But I dont like CEL lights being on.
ideas?

 

So you think that P4131 is the secondary air pump?

The book says "Compressor Connection Signal". I took that to be the AC Compressor.

https://www.ferrarichat.com/forum/posts/149125041/

P1212 is related to "Lambda regulation" on the 2.7 car. Is there a reason why you looked at the MAF sensors?

 

The A/C compressor codes on the 5.2 don't make a whole lot of sense

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If the Motronic ECU is looking at the signal on pin 40, this will be 12 volts, I would imagine, with the compressor running. Zero volts with the compressor not running.

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1212 is long term fuel trim. Could be a bad O2 sensor, exhaust leak (before the O2 sensor like a cracked header), ... Cracked headers on 1-4 side are common.

 

I keep forgetting how to read this chart.

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For a particular numerical code, to you match the corresponding Error Type line and the line above.... or the line below? And why are there two 1212 codes?

 

A or B?

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Oh, yes, I forgot. it's LT fuel trim or ST fuel trim. In either case, it's fuel trim. And if the light come on and goes off, it likely ST fuel trim. Still, look for exhaust leaks or bad O2 sensor.

 

I dont know the issue yet. I did read several references in prior posts that the compressor might be air pump so I checked.

Thanks all for your suggestions. The search continues

 

I'm putting my money on the A/C compressor. The Secondary Air Pump is used in too many documents.

Here's the check for the compressor (at the Motronic ECU plug):

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The first columns are Motronic ECU pin numbers.

You can probably do this with the plug disconnected on each Motronic ECU and do wiring checks on the harness plug. Normally you would use a breakout box or remove the backshell from the ECU connector and backprobe the sockets.

According to this, you don't need to have the engine running.

 

Seems the jury is in.
I had an extra Bosch O2 sensor so I temp. put it in place. ran out for a few miles not a CEL to be blinked! Woo Hoo!
though I've certainly gone through a few O2 sensors on this car. All Bosch, all The correct one.

I'll check this one when I secure the new one in place. looks like the black coat wore through. perhaps there was a short to frame.