Question about Volvo S60
With the engine off and the battery negative cable disconnected, check all electrical connections at the o2 sensors, MAF and elsewhere. Under-hood temperatures tend to cause some oxidation on the terminals themselves. I've seen this issue with nearly every Volvo I've owned. Use electronics cleaner and dielectric grease on the connectors, especially on the MAF connector.
P0240 (Catalyst working below efficiency threshold) means the downstream (2nd) o2 sensor is not moving. The reason for this sensor's existence is pretty simple - detect catalyst efficiency and possibly failure in the field. The upstream sensor must be in good condition and not 'lazy', meaning it is slow to respond to the oxygen levels coming out of the exhaust. It must be quick to respond. The downstream o2 sensor, however, usually doesn't change state as much, meaning the catalyst is doing its job. The idea is that if that downstream sensor starts to mimic the upstream o2 sensor activity, catalytic function can be inferred to be less than normal. Ensure the connections are good on both sensors. Replacing only the upstream o2 sensor will not cure this. Catalytic convertor failure is rare in the field but if you have been running rich, it's possible a large quantity of unburned fuels have destroyed or eroded the substrate. The only way to tell is put a scan tool on the car and monitor both sensors, capturing any freeze frame data along the way. Upstream sensor should be rapidly changing state and downstream should be changing state much more slowly.
P0100 (MAF circuit - malfunction) usually points towards wiring issues or problems with the connector, especially if the MAF is known good.
P0089 (Fuel pressure - regulator) could be a worn fuel pump, clogged filter or the regulator itself. Have the fuel system pressure tested, verifying components along the way.
If all checks pass at this point, it is possible that the connections at the ECM itself need cleaning (do not unplug the ECM with the battery negative cable connected). If you perform this procedure do so with extreme caution and scrupulous cleanliness. Allow the cleaner to completely evaporate off the terminals or there could be a serious short condition that will destroy that 600 dollar computer.
Posted on Oct 22, 2013
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Posted on Jan 02, 2017
The catilytic convertor is at fault and needs replacing.
Have it checked first for a 02 sensor can throw this code as well. If the convertor is turning red on the outside it is junk status. Also the engine will sound like its starving for fuel
Posted on May 17, 2010
P0100 OBD-II Trouble Code
Mass Air Flow (MAF) Circuit Malfunction
Basically this means that there's a problem with the Mass Air Flow (MAF) sensor or circuit.
You will likely not notice any serious driving problems, but there may be symptoms like a general decrease in power or sluggishness.
A code P0100 may mean one or more of the following:
* The MAF may be disconnected, or a wiring connection may be bad.
* The MAF sensor may be faulty.
Use an OBD II Reader (or go tou your local parts store and they will for free) and reset the code and see if it comes back.
Then start with the cheapest, easiest repair procedures:
* Check the Mass Air Flow Sensor wiring/harness is connected properly and that there are no broken / frayed wires.
* Unplug and reconnect the MAF wiring harness a few times to clear the contacts.
* Check the voltage of the MAF sensor (refer to a repair manual for vehicle specific information).
* Replace the MAF sensor.
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Posted on Sep 28, 2010
SOURCE: 1999 toyota tacoma maf p0100
what you have here is a faulty temperature sensor so its telling the computer the engine is still cold ,right so you know the fault but where this sensor is i have no idea sorry only europeon motors and these of this model are all diesel with mainly manual gearboxes
Posted on Apr 14, 2012
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A/T Diagnosis Communication Line Malfunction Possible Causes:
Trouble Code: P0100
Mass Airflow Sensor Circuit Malfunction
Air Intake leaks located after the MAF sensor assembly MAF sensor signal circuit is open, shorted to ground or power MAF sensor has failed PCM has failed
Trouble Code: P1605
TCM communication line circuit is open or shorted to ground TCM communication line circuit shorted to VREF or power (B+) TCM or PCM has failed TSB 01-004 (01/01) contains information related to this code
For the P0100, check the connector on top of the MAF sesnor for looseness or corrosion. Connector is on top in piocture below.
A/T Diagnosis Communication Line Malfunction
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