General: '55 S40 1.8: Throttle Potentiometer Faulty Signal...

[eric19371]

Hope somebody can help with an issue that has appeared on my wife's S40 (1.8 petrol, '55 plate, manual).

We were out today and twice she got a "Reduced engine performance" message. Stopped, turned car on and off, error gone. On both occasions the car seemed to run OK. I also got it twice last week and on one of those occasions it became very sluggish.

I connected my iCarsoft diagnostic unit to it when we got home late this evening and it gave the following three errors.

0121 - Electronic throttle unit, potentiometer 1, Faulty signal
0221 - Electronic throttle unit, potentiometer 2, Faulty signal
2135 - Accelerator pedal (AP) position sensor, Faulty signal

The 2135 error has actually been there for a little while but hasn't seemed to cause any problems so I have ignored it.

Also the throttle body was replaced 12-18 months ago after it started idling badly and kept stalling. Replacing the throttle body resolved the issue. (the new one was a generic one off eBay, if I need to replace it again I will get a Bosch one)

I am going to clean the connections to the throttle body and accelerator pedal tomorrow with contact cleaner. I also understand that if I put the key in without starting the engine then after a minute it goes through some sort of calibration process on the throttle body.

Has anybody else seen this and/or has any advice?

[Clan]

Originally Posted by eric19371

Hope somebody can help with an issue that has appeared on my wife's S40 (1.8 petrol, '55 plate, manual).

We were out today and twice she got a "Reduced engine performance" message. Stopped, turned car on and off, error gone. On both occasions the car seemed to run OK. I also got it twice last week and on one of those occasions it became very sluggish.

I connected my iCarsoft diagnostic unit to it when we got home late this evening and it gave the following three errors.

0121 - Electronic throttle unit, potentiometer 1, Faulty signal
0221 - Electronic throttle unit, potentiometer 2, Faulty signal
2135 - Accelerator pedal (AP) position sensor, Faulty signal

The 2135 error has actually been there for a little while but hasn't seemed to cause any problems so I have ignored it.

Also the throttle body was replaced 12-18 months ago after it started idling badly and kept stalling. Replacing the throttle body resolved the issue. (the new one was a generic one off eBay, if I need to replace it again I will get a Bosch one)

I am going to clean the connections to the throttle body and accelerator pedal tomorrow with contact cleaner. I also understand that if I put the key in without starting the engine then after a minute it goes through some sort of calibration process on the throttle body.

Has anybody else seen this and/or has any advice?

Back 13 years ago there was a service fix for throttle problems , the plug was not a tight fit in the throttle recess so would move when the engine moved , this would wear the terminals , you should not be able to wiggle the plastic terminal housing on the loom which plugs in . if you can move it put a layer of insulation tape around it to take up the gap .

[eric19371]

Originally Posted by Clan

... if you can move it put a layer of insulation tape around it to take up the gap .

Thanks for that. It didn't seem to wiggle but it wasn't a snug fit so I gave that a go. Seems to fit firmly but the error is still there. :-(

I checked and only got the last throttle body in May last year, of course just outside the 1 year warranty period the seller offered with it. It was a generic unit advertised for a Ford Focus but had the same part number (they both use the same 1.8 engine) and until now worked fine. The part number was 4M5G9F991FA and cost me £109.

I can now get the same part for about £50 various UK eBay sellers but I am understandably worried about quality so does anybody have a recommendation for a brand and seller I can get a quality one from if I need to replace it?

[eric19371]

I have now replaced the throttle body and for two days it gave no problems but now they are back, with friends...

Yesterday it came up with the dreaded "Reduced engine performance" message three times on a short drive from a local shopping center, a drive of just over 8 miles. Stopping and restarting the engine still clears the message but when I went to check it this morning the engine emission light was on. Not great news but at least I would get some codes that might point towards the cause.

P2110 - Throttle Actuator A Control System - Forced Limited RPM
P2111 - Throttle Actuator A Control System - Stuck Open
2135 - Accellerator Pedal (AP) position sensor, Faulty signal
2111 - Electronic throttle unit, Internal fault *
2110 - Electronic throttle unit, Internal fault *
0221 - Electronic throttle unit, potentiometer 2, faulty signal

Pretty much the same issues as I had before but with a new throttle body I am wondering if the fault is with the ECM (engine control module) or the wiring.

Not sure what to do next except take it to a local independent Volvo specialist.

Looking for ideas as what to check next, or at least the details of a recommended Volvo independent in the mid-NW area of Kent (I am halfway between Maidstone and Dartford).

[eric19371]

Took it to a local garage and they connected their SnapOn diagnostics equipment to the car and found loads of saved error codes that my iCarSoft reader didn't pick up (sunroof, rain sensor, etc.). There were no significant errors with the engine at that time so they cleared all the codes to get it back to zero and told me to bring it straight in next time it gives a problem.

I have noticed however that when slowing and removing my foot from the accelerator the revs drop very low, and it has almost stalled on a couple of occasions. Would love to get it connected to a VIDA system to see if that gives any more information.

[cam147]

Did you get it fixed yet? My v50 1.8 has similar problems ie replaced tps and now going into limp mode . Thanks

[superhifi]

As you're getting errors from both the throttle body and the pedal i'd be inclined to check the connections to the ECU module.

You might want to check VIDA to be sure, but I think the ECU is situated in front of the pasenger side front wheel, behind the arch lining.

[Clan]

Originally Posted by eric19371

I have now replaced the throttle body and for two days it gave no problems but now they are back, with friends...

Yesterday it came up with the dreaded "Reduced engine performance" message three times on a short drive from a local shopping center, a drive of just over 8 miles. Stopping and restarting the engine still clears the message but when I went to check it this morning the engine emission light was on. Not great news but at least I would get some codes that might point towards the cause.

P2110 - Throttle Actuator A Control System - Forced Limited RPM
P2111 - Throttle Actuator A Control System - Stuck Open
2135 - Accellerator Pedal (AP) position sensor, Faulty signal
2111 - Electronic throttle unit, Internal fault *
2110 - Electronic throttle unit, Internal fault *
0221 - Electronic throttle unit, potentiometer 2, faulty signal

Pretty much the same issues as I had before but with a new throttle body I am wondering if the fault is with the ECM (engine control module) or the wiring.

Not sure what to do next except take it to a local independent Volvo specialist.

Looking for ideas as what to check next, or at least the details of a recommended Volvo independent in the mid-NW area of Kent (I am halfway between Maidstone and Dartford).

As you have a throttle pedal fault code I would say it is the connector terminals on both the throttle pedal and the CEM under the glove box . They can "fret" over the years and loose their grip on the pins . The only specialist is the volvo dealer who has the experience of these particular codes for the last 10+ years and knows exactly what to do ... If it were me i would also replace the white signal wire from pedal to CEM as it disappears up behind the dash and could be damaged where you will never see it .

[eric19371]

Having the garage clearing the codes with their superior code reader worked miracles but it still seemed to want to stall every now and again so I thought I would adjust the idle adjustment screw.

Oops, big mistake. Turns out you are not supposed to do this and I broke it. Back on with the old throttle body (cheap Ford Focus part from eBay) so it would at least run and it seems to have fixed itself. The wife has been driving the car since the last post with no issues. I have a reconditioned throttle pedal in the garage as there is still one throttle pedal position error but if the car behaves itself then I see no point in installing it.

[Clan]

Originally Posted by eric19371

Having the garage clearing the codes with their superior code reader worked miracles but it still seemed to want to stall every now and again so I thought I would adjust the idle adjustment screw.

Oops, big mistake. Turns out you are not supposed to do this and I broke it. Back on with the old throttle body (cheap Ford Focus part from eBay) so it would at least run and it seems to have fixed itself. The wife has been driving the car since the last post with no issues. I have a reconditioned throttle pedal in the garage as there is still one throttle pedal position error but if the car behaves itself then I see no point in installing it.

The pedal itself is never at fault , it is as i described above...