DTC Code PO181

[bschmitz]

This is my first post so bear with me.
The check engine light came on my 2002 D/A with 60,000 miles, I put my scan tool on and the code came up as PO181, fuel temp sensor. I cleared the code, light went off, have drove it over 2000 miles since then and the light has not came back on. Truck runs great. Should I be concerned or will the code come back up at some time?

[DmaxMaverick]

Welcome to the Forums!

The diagnostic procedure is pretty lengthy. Start by check the connectors at the MAF and fuel temp sensor. If the fuel temp and IAT (intake air temp) are more than 18°F (10°C) apart at a cold start, it will set the code, but only on the second cold start the conditions are met. Either sensor with poor contact can skew the ECM input values. In any case, P0181 should not set on a warm engine, or while driving. The SES will reset after 3 consecutive successful starts when the conditions are correct, and the DTC in history will clear after 40 consecutive warm up cycles with no failure.

If you have a scanner or Predator programmer, you can read the IAT and FT to see which one is out of spec. If the truck sits overnight, both should be near ambient temp and very close to each other. If one is way off, it should indicate which sensor is reporting the bad reading.

[WhiteTruck]

Did this occur after using the block heater?? If so, there is a calibration update for this per TSB 02-06-04-058 regarding setting a false code due to heater usage.
This TSB 06-06-04-027 updates the block heater cord to one with a thermostat to prevent operation above 0 degrees. I would do just the cal update 1st if this pertains to your problem and see if that corrects it 1st.
Since I can't tell where you are located by your post, this obviously doesn't apply if you live in Phoenix!

[bschmitz]

Did this occur after using the block heater?? If so, there is a calibration update for this per TSB 02-06-04-058 regarding setting a false code due to heater usage.
This TSB 06-06-04-027 updates the block heater cord to one with a thermostat to prevent operation above 0 degrees. I would do just the cal update 1st if this pertains to your problem and see if that corrects it 1st.
Since I can't tell where you are located by your post, this obviously doesn't apply if you live in Phoenix!

When this happened we were in Kansas where the temps were very cold, in the low teens, I had the truck pluged in the night before the check engine light came on with the code. I think you hit the nail on the head. Thanks for the info.

[DmaxMaverick]

That makes sense. I knew of the bulletin, but the relationship between the fuel temp and block heater use didn't match up. They don't cross paths, electrically, and the PCM gets no feedback from the block heater. I've never used the block heater (even in sub zero temps), so was going on what others report.

However......Using the block heater also heats the fuel rail after a period of time. The FT sensor is located there. This would create a situation where the sensor could see a much higher temp than the IAT sensor, which is located on the MAF sensor.