[5th Gen : 08+]: 2012 Caravan PO128
#1
12-31-2020, 06:21 PM
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2012 Caravan PO128
Hi,
I have a 2012 Dodge Caravan. It is throwing a po128 code. I replaced the thermostat, but it is still throwing the code and the temperature gauge inside the car's dashboard, while it appears functional, is only going about a quarter of the way up. What is the next step? Thanks so much!
I have a 2012 Dodge Caravan. It is throwing a po128 code. I replaced the thermostat, but it is still throwing the code and the temperature gauge inside the car's dashboard, while it appears functional, is only going about a quarter of the way up. What is the next step? Thanks so much!
#2
01-02-2021, 02:14 PM
Before you dive too deep into this, there’s a few things to note:
1) The dash gauge is logic controlled. The instrument cluster receives engine temperature via data from the PCM and controls the gauge position accordingly. There is no direct link between the cluster and temp sensor, so using the gauge isn’t dependable. The best way to read engine temp is using a scan tool, but If you have the driver information center it should give you a temp reading under “vehicle info.”
2) Extremely low ambient temperature can cause this code to set, particularly if the van is parked outside.
3) Low coolant level can also set this code. If you have a rear heater core, make sure the system is completely bled by running both heater cores on high heat, high blower fan for at least 5 minutes once the engine is warm. It will help bleed air from the rear core to park on an incline with the engine up.
Also, coolant level should be checked in the reservoir with the engine hot and shut off. Checking and Filling at the radiator is only recommended during system service.
That said, here’s some things to check.
1) Check the freeze frame data for the code - see what the intake air temp (IAT) is. The PCM uses IAT (in conjunction with engine run time and load) to calculate a predicted value for what engine temp should be. If the IAT is excessively high or low, use a basic scan tool (or phone app with dongle) to read IAT with the sensor unplugged. It should read -40*F. Then use a 3A fused jumper wire to momentarily jump the circuits for the IAT together - it should now read about 250*F. If those tests are successful, the wiring is good and I’d recommend replacing the IAT.
NOTE: IAT is somewhat affected by engine temp. The longer the engine runs, the warmer it gets in the engine bay and therefore, the warmer the intake air will be. Use your best judgement to determine if the IAT reading is excessive for the engine run time (also recorded in freeze frame data).
2) Perform the same wiring checks on the ECT as you did on the IAT while watching live data. Any readings other than -40 when open or 250 when jumped together indicates a problem with the wiring.
Post your results for the tests if you need more help - diagnosis can go a few different directions depending on the results.
1) The dash gauge is logic controlled. The instrument cluster receives engine temperature via data from the PCM and controls the gauge position accordingly. There is no direct link between the cluster and temp sensor, so using the gauge isn’t dependable. The best way to read engine temp is using a scan tool, but If you have the driver information center it should give you a temp reading under “vehicle info.”
2) Extremely low ambient temperature can cause this code to set, particularly if the van is parked outside.
3) Low coolant level can also set this code. If you have a rear heater core, make sure the system is completely bled by running both heater cores on high heat, high blower fan for at least 5 minutes once the engine is warm. It will help bleed air from the rear core to park on an incline with the engine up.
Also, coolant level should be checked in the reservoir with the engine hot and shut off. Checking and Filling at the radiator is only recommended during system service.
That said, here’s some things to check.
1) Check the freeze frame data for the code - see what the intake air temp (IAT) is. The PCM uses IAT (in conjunction with engine run time and load) to calculate a predicted value for what engine temp should be. If the IAT is excessively high or low, use a basic scan tool (or phone app with dongle) to read IAT with the sensor unplugged. It should read -40*F. Then use a 3A fused jumper wire to momentarily jump the circuits for the IAT together - it should now read about 250*F. If those tests are successful, the wiring is good and I’d recommend replacing the IAT.
NOTE: IAT is somewhat affected by engine temp. The longer the engine runs, the warmer it gets in the engine bay and therefore, the warmer the intake air will be. Use your best judgement to determine if the IAT reading is excessive for the engine run time (also recorded in freeze frame data).
2) Perform the same wiring checks on the ECT as you did on the IAT while watching live data. Any readings other than -40 when open or 250 when jumped together indicates a problem with the wiring.
Post your results for the tests if you need more help - diagnosis can go a few different directions depending on the results.
#3
01-02-2021, 09:49 PM
#4
01-02-2021, 09:52 PM
my 2001 van is just rusted to much to put any more money in it got 4 grand already tied up in it so i thoguht this car from florida no rust anda 2003 chrysler town n country which looks identical to my dodge ..might be a good buy just wanna see if all the new partson my dodge will fit it..please n ty.