'94 940 fault code 2-3-1 and 1-1-3

[Mn10]

Hi everyone,

My check engine light is on and when I went to retrieve the codes, I got the 1-1-3 code and the 2-3-1 code. Both of which according to the list I have suggest fuel trim. According to my mechanics OBD I scanner the 2-3-1 code shows up as the engine temp sensor (I think it’s also called coolant sensor), I’m taking it to him next week to swap that out, but he isn’t sure what the 1-1-3 could be as he has changed the oxygen sensor and to him it seems as if it’s most probably the mass air flow sensor. (Here in Aus it’s hard to find a refurbished one, there are only used ones available which you can’t be sure if they work until after you’ve tried them). Has any one had any experience with this? This problem intrigues me, and I’ll be sure to post back here next week with my mechanics input and solution

Edit: Also my mechanics checked for vacuum leaks and there are none; and if I need a refurbished MAF sensor and can’t find one I have seen some on IPD USA, but ofcourse it’s not easy on the wallet.

Edit: I forgot to mention that the car has poor acceleration, feels a little low on power and of course with the air con on, the acceleration off the line is basically a struggle. Fuel consumption doesn’t seem too bad, not sure if it’s been affected at all.

Just in case, it’s a 1994 Volvo 940 2.4L NA model. (LH 2.4)

[93Regina]

1994 Volvo 940 2.4L NA model. (LH 2.4)

AMM Numbers

Bosch - 8251497
Delphi - AF10199
Interchange Numbers: 5517020, AF10199, AF10199-11B1, 3517020, 8251497, 8602792，MF20044, 336-59094 ,5517020, 280212016

Diagnostic Error Codes 2-3-1 and 1-1-3 -

Code 2-3-1 suggests the oxygen sensor encounters an amount of oxygen in the exhaust that is not consistent with the mass of air the fuel control ECU calculates, or measure, through the connected air mass meter (AMM/MAF mass air flow) or sensor.

1-1-3 Fault in injector (Break in [wiring] lead. clogged. etc.) - The cause is the measure resistance measure through the connected wiring with the electromagnet field coil winding in the injectors the ECU encounters.....

Have you smelled the exhaust when warming up and warmed up? If rich, you'll easily or slightly smell gas smell in the exhaust. If too lean, the exhaust will smell exceedingly sweet and be much hotter than normal.

Other causes may be (usually causing a lean condition - in no order):
- a faulty injector ground
- bad connection connection at one of more connectors
- bad connection or faulty radio suppression relay (See Dave Barton reference, below.)
- Faulty cold start valve (another stupid name for a cold start injector) or connection to it
- corrosion of the connection at the wire harness and ECU connector interface.

If rich under this fault code:
- leaking injector
==================

[RickHaleParker]

.According to my mechanics OBD I scanner the 2-3-1 code shows up as the engine temp sensor (I think it’s also called coolant sensor),

You need to find out which control module he is reading the codes from.
Control modules: A1 - A7 & B1 -B5

1-1-3 is one of the two below depending on which control module is being read.

• 1. Transmission control module (TCM) fault.
  2. Fuel gauge open circuit.

2-3-1 is one of the four below depending on which control module is being read.

• 1. Throttle position (TPS) sensor sporadic.
  2. Long term fuel trim, part load.
  3. Ventilation damper motor position sensor open circuit or shorted to 12 volts.
  4. Left belt tensioner short circuit.

[93Regina]

Volvo use to have different versions (electrically and mechanically) of their vehicles, depending upon which country they were delivered to.

LH 2.4, to my awareness did not have OBD-1.

So the question to the OP is, what transmission does your vehicle have? And, in engine compartment, does this box exist, as seen at this site: Engine and OBD Diagnostic Codes?

[Mn10]

Yes sometimes I can smell gas coming from the exhaust on cold engine, and sometimes I can smell gas when I come and park it after a drive; but most of the time there is no smell (maybe there is a sweet smell I don’t realize, I’ll check on my next drive).

Both the codes are coming from module A2. I found this out by reading the codes using the in built diagnostic tool.

Sorry I hadn’t clearly pointed this out in my original post. My vehicle is equipped with OBD-I and yes it has both the boxes (A&B) under the bonnet on the passenger side. This is how I read the codes before posting them on here.

Also my vehicle has either an AW70/AW70L or an AW71 transmission. I can’t tell for sure.

Thank you both for your help.

[RickHaleParker]

Missed the LH 2.4.

For LH 2.4 Control module A2:
1-1-3 Fuel trim (lambda control) too lean or rich. Mixture incorrect; O2S wiring fault.
2-3-1 Fuel trim (lambda control) too lean or too rich at part load. If too lean: air leaks, low fuel pressure, bad sensor.

Check the wiring and voltages to the O2 sensors. Check for low fuel pressure. Check for Air leaks.

[Mn10]

O2 sensor was replaced a few years ago. Wiring seems fine. I’ll check the voltages soon and see how that’s going.

My mechanic has checked for air leaks on more than one occasion and never found anything. I think the fuel pressure is ok but I’ll check on that. Yeah it could be a bad engine temp sensor or something similar, but I’ll look at the other things before.

[93Regina]

engine temp sensor

ECU's temp sensor, which feeds a signal to LH and ignition computers, when they start failing, sends a colder "signal" to these computers.

Test - Unplug this temp sensor....when done, 32°F will be the start programmed value, and then run on 70°F programmed value.

>car has poor acceleration

Need to know if running rich or lean....leanness could suggest AMM....also, check brake's vacuum unit via plugging it off from intake manifold. If sucking air, this extra air would not be accounted for via AMM...and engine would be running lean initially.

Once engine is started, in a short period of time, the O2 sensor will be operational, and LH will be adjusting fuel/air mixture....hence, all air must pass thru AMM.

[93Regina]

In US, OBD-1 has a specific meaning to mechanics - While OBD-I required a technician to physically plug a scan tool into the diagnostic port, OBD-II supports wireless operation, via a Wi-Fi or Bluetooth adapter.

https://www.carfax.com/blog/difference- ... and-obd-ii

Maybe a Volvo shop has a scan tool, but to my awareness, non Volvo mechanics have never seen one. OBD-1 in US means a hand-held device that is physically plugged into a socket designed for it. OEM shops did have a different setup for evaluating.

[Mn10]

Sorry for the late response, got caught up this week. I haven’t tested the ECU’s engine temp sensor yet.

I’ve checked for vacuum leaks from the brake unit and didn’t find any. (I also should have mentioned that the brake booster unit was replaced a couple years ago with a reliable refurbished one as the old one popped a leak).

I think it’s the same deal here in Australia, you have to buy a scan tool from Volvo - my mechanic has one, which he plugs in to the port to read the codes. It also gives him information on the codes.

It’s going in for it’s regular service tomorrow anyway, I’ll post what goes on with the issue in this thread after I get it back.