Codes P0120-2 and P0220-2, idles rough?

KERRIE7289

MEMBER
2007 VAUXHALL AGILA
1.0L
3 CYL
2WD
MANUAL
54,000 MILES

Car is rough idle but then smooths out when increased RPM. Done a diagnostic and code P0120-2 and P0220-2 were displayed. The codes do clear when I used the OBD2 reader. I have looked at the position of TPS and when car on and the engine off TPS calculated at 7.5% but then when the engine on, the calculated TPS drops to 1.5%. When I remove the TPS the rough idle stops, although the car surges looking for the TPS.

1 Reply

BORIS K

MECHANIC
799 POSTS

Hello,

I would suggest checking 5V supply, ground and feedback voltage back to the ECM.
For this the scan tool must be able to give you live data reading.
You will also require a voltmeter.
See image 1 below for the pin out from TPS to the ECM connector X47.
See image 3 for X47 location.

How to use a voltmeter:
https://www.2carpros.com/articles/how-to-use-a-voltmeter

Testing
Ignition off
Disconnect the connector at the TPS, see image 2
Connect voltmeter probe to pin 2 and other to battery ground terminal
Check that the resistance is less than 10ohm
Remove probes, Ignition on
Connect voltmeter probe to pin 3 and battery ground terminal
Check that you have 4.8-5.2V
Next connect the scan tool.
Connect pin 3 to pin 6 using a jumper wire.
Check that you have supply voltage as live data for the TPS sensor 1
Next disconnect pin 6 and connect jumper to pin 5
Check in live data that you have supply voltage as live data for the TPS sensor 2
If the live data is okay, then this proves that the ECM is receiving a plausible signal and it points towards a possible faulty TPS.

Cheers, Boris

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