HI, i have a 93 940 N/A wagon, the first time i took it to get tested it failed on Nox @ 1300 ppm. The cat is new so i pulled the codes and it came up as being the O2 sensor so i replaced that. the seconed time around on the test it failed again @ 1052 ppm on Nox. the only two codes i get now are 122 and 221 on socket 2. ive cheaked the and replaced the AMM and the ICV and got no changes. Any thoughts?
Sam
93-940 Emmisions issue
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billofdurham
- MVS Moderator
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- Year and Model: 855, 1995
- Location: Durham, England
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Welcome to Matthew's Volvo Site.
1-2-2 is Intake Air Temperature sensor signal missing or defective.
Possible causes are: A short circuit to earth (ground) in the cable, connectors or sensors.
Contact resistance in the terminals.
Poor earth (ground) for the signal earth.
Check all the earth contacts around the MAF and IAT and check the terminal contacts for corrosion/oxidization. Also, whilst you are busy at the plug test for voltage between terminal 1 and earth. Switch ignition on, disconnect the plug and connect a voltmeter between terminal 1 and earth. Reading should be approximately 5 volts.
2-2-1 is heated oxygen sensor (HO2S) signal missing or defective.
Possible causes are: open circuit, short circuit to earth or voltage in the cables to the HO2S.
Open circuit, short circuit to earth or voltage in the HO2S.
Contact resistance in the terminals to preheating.
No power to HO2S.
To check the signal from the HO2S you need a voltmeter which is connected between the terminal 1 ( a 1-pin connector at the bulkhead (firewall) and earth. Start the engine.
If the readings are:
1. Oscillating between 0.1 volts and 1.2 volts check the terminals for loose connections.
2. A constant low value, with the engine still running disconnect the 1-pin connector and connect the voltmeter between the 1-pin and earth. The voltmeter should read 1.2 volts after a moment.
3. A constant at approximately 1.2 volts check the cable between the connector and control module #24 for an open circuit.
4. A constant high value over 1.4 volts or oscillates with a top value higher than 1.4 volts, with the engine still running connect the voltmeter between terminal 1 on the 2-pin connector and earth. The voltmeter should read approximately 0 volts.
Bill.
1-2-2 is Intake Air Temperature sensor signal missing or defective.
Possible causes are: A short circuit to earth (ground) in the cable, connectors or sensors.
Contact resistance in the terminals.
Poor earth (ground) for the signal earth.
Check all the earth contacts around the MAF and IAT and check the terminal contacts for corrosion/oxidization. Also, whilst you are busy at the plug test for voltage between terminal 1 and earth. Switch ignition on, disconnect the plug and connect a voltmeter between terminal 1 and earth. Reading should be approximately 5 volts.
2-2-1 is heated oxygen sensor (HO2S) signal missing or defective.
Possible causes are: open circuit, short circuit to earth or voltage in the cables to the HO2S.
Open circuit, short circuit to earth or voltage in the HO2S.
Contact resistance in the terminals to preheating.
No power to HO2S.
To check the signal from the HO2S you need a voltmeter which is connected between the terminal 1 ( a 1-pin connector at the bulkhead (firewall) and earth. Start the engine.
If the readings are:
1. Oscillating between 0.1 volts and 1.2 volts check the terminals for loose connections.
2. A constant low value, with the engine still running disconnect the 1-pin connector and connect the voltmeter between the 1-pin and earth. The voltmeter should read 1.2 volts after a moment.
3. A constant at approximately 1.2 volts check the cable between the connector and control module #24 for an open circuit.
4. A constant high value over 1.4 volts or oscillates with a top value higher than 1.4 volts, with the engine still running connect the voltmeter between terminal 1 on the 2-pin connector and earth. The voltmeter should read approximately 0 volts.
Bill.
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Work was good - retirement is better.
1996 850GLT 2.5 20v Estate Manual.
1995 Peugeot Boxer 2.5Tdi Autosleeper.
Previously:
1984 244DL, Manual, Beige.
1987 744GLE, Manual, Green.
1991 960 3.0 24v, Auto, Silver.
1994 940T Wentworth, Auto, Blue.
1996 850GLT 2.5 20v Estate Manual.
1995 Peugeot Boxer 2.5Tdi Autosleeper.
Previously:
1984 244DL, Manual, Beige.
1987 744GLE, Manual, Green.
1991 960 3.0 24v, Auto, Silver.
1994 940T Wentworth, Auto, Blue.
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