Questions and Answers

Volvo 850 DTCs 1-1-3, 2-3-2 and 5-1-2 Q. Hi, I've got a 1994 Volvo 850 wagon 2.5 liter non-turbo engine. I've been having problems with getting it cranked after a -33° morning two months ago. I got a Mass Air Flow code and today I got it running but another code came on and I noticed it was running sluggish. I got a (A2) socket codes: 1-1-3, 5-1-2, 2-3-2. What should I start to look at for a remedy to these codes?

A. Here is a list of the trouble codes and what they mean.

These are the things you need to check for each DTC. Basically it looks like you have a bad Mass Air Flow Sensor or O2 Sensor.

1-1-3 Short Term Fuel Trim (Integrator), Upper Limit

Condition(s) for DTC

The short term fuel trim value is a measure of the manner in which the injection period included in the basic MFI module program must be varied to ensure that the engine is supplied with the optimum air/fuel mixture. This optimum mixture corresponds to a value of Lambda = 1. If the engine is running lean, the short term fuel trim will extend the injection period to restore the optimum mixture. A DTC will be recorded if the engine runs so lean that the short term fuel trim reaches its upper limit and remains there for 166 seconds.

Fault source(s)

• Heated Oxygen Sensor (HO2S ) signal lead short-circuited to ground.
• Heated Oxygen Sensor faulty.
• Contact resistance and oxidation in Mass Air Flow (MAF) Sensor connector.
• Mass Air Flow Sensor faulty.

2-3-2 Long Term Fuel Trim, Idling, Upper Limit

Condition(s) for DTCs

The MFI module receives information from the Heated Oxygen Sensor (HO2S ) if the air/fuel mixture is too lean in the idling range (2-3-2) or in the part-load range (2-2-1). In this case, the HO2S signal will usually be less than 0.5 Volts . The MFI module short term fuel trim compensates for this by enriching the mixture so to maintain a value of Lambda = 1 . Deviation of the short term fuel trim mid-setting from its normal value will be compensated by the long term fuel trim. Enrichment by the long term almost to a maximum (upper limit) will be interpreted as abnormal and the DTC will be recorded.

Fault source(s)

• Open-circuit in HO2S heater supply or signal lead.
• HO2S heater signal lead short-circuited to ground or supply.
• Faulty HO2S.
• Contact resistance and oxidation in HO2S connector.
• Faulty Mass Air Flow (MAF) Sensor.
• Low fuel pressure.
• Air leakage.
• Incorrect sensor signals.

5-1-2 Short Term Fuel Trim (Integrator), Lower Limit

Condition(s) for DTC

The short term fuel trim value is a measure of degree to which the injection period in the basic MFI module program must be varied to ensure that the engine is supplied with the optimum air/fuel mixture. This optimum mixture corresponds to a value of Lambda = 1 . If the engine is running rich, the short term fuel trim will reduce the injection period to restore the optimum mixture. A DTC will be recorded if the engine runs so rich that the short term fuel trim reaches its lower limit and remains there for 166 seconds .

Fault source(s)

• Heated Oxygen Sensor (HO2S ) signal lead short-circuited to ground.
• HO2S faulty.
• Contact resistance and oxidation in Mass Air Flow (MAF) sensor connector.
• MAF sensor faulty.