esi2004

Check engine light came on this morning.

Got 3 stored codes(Codes and description from OBD scan tool):

C2100 - Low batt Voltage (had this one about a month ago also)

P0071 - Ambient Air Temp Sensor (just came on)

P0514 - Batt temp sensor (just came on)

Haven't checked batts yet they are about 4 yrs old.
Are these just from the cold or what? Was -5 last night and about 12 this morning. I just replaced my block heater last week and I have heated battery blankets that plug in with block heater. Could my batts actually be getting too hot? Never had these codes before(except low volt C2100)

xcc_rider

From the 2008 FSM:

P0514-Theory of Operation
There are two parts to this fault code, a key on check and a rationality check. After an 8 hour cold soak, at key ON the readings for the ambient air temperature, battery temperature and intake air temperature and coolant tempera- ture are all compared. If the temperatures differ more than a calibrated amount, then the appropriate sensor fault code would be recorded. The key on monitor is disabled for ambient temperatures below -6.7° C (200 F). This mon- itor looks for all the sensors to be grouped on one temperature or, in the case that the monitor fails, three sensors grouped at one temperature and one outlier. In the case that all four sensor values are distributed over a range of temperatures this diagnostic will not run. A block heater is one possible cause of such a distribution. The rationality check is referred to as a dither. The dither looks at the temperature reading from the sensor over time and ensures that it changes. This monitor is used to detect a "stuck" sensor. If the sensor reading does not change over a cal- ibrated time limit, the fault will be recorded. Both the key-on and dither portions of this rationality error require that the diagnostic fails in two consecutive drive cycles before the MIL lamp is lit. During this time the ECM uses an default value for the intake air temperature. The ECM turns off the MIL lamp when the diagnostic runs and passes in 4 consecutive drive cycles.
• When Monitored:
Key on engine off and while engine is running.
• Set Condition:
At key on engine off, the intake air temperature sensor reads differently than the battery temperature and ambient air temperature sensors. Or while the engine is running the ECM does not read a change in value from the intake air temperature sensor over time.
Possible causes
BATTERY TEMP SENSOR
INTERMITTENT CONDITION


P0071 (rationality) you didn't say which one so I'll list both
Theory of Operation
This DTC is set in the ECM. The inlet air pressure is part of the Inlet Temperature/Pressure Sensor which is located in the top of the air cleaner box. The Inlet Air Temperature Sensor performance looks at the outputs of four tem- perature sensors and compares them under cold start conditions. Following a start to run delay time, the outputs of the inlet air, engine coolant, intake air temperature and battery temperature sensors will be compared. If the engine coolant, intake air and battery temperature sensors agree and the inlet air temperature does not agree. the inlet air temperature sensor is declared irrational. This diagnostics also checks for a change in sensor value over a period of time. This is to verify the sensor is not stuck. The ECM will illuminate the MIL lamp after this diagnostic runs a fails in two consecutive drive cycles. The ECM will turn off the MIL lamp once the diagnostic runs and passes in four consecutive drive cycles.
• When Monitored:
While the engine is running.
• Set Condition:
The ECM does not read a change in value from the sensor over time. The ECM value after a cold soak for the inlet air temperature sensor varies from other engine temperature sensors.
Possible Causes
INLET AIR TEMPERATURE SENSOR
INTERMITIENT CONDITION

P0071 (performance)
• When Monitored:
Engine off time is greater than 480 minutes. Ambient temperature is greater than 40 C (380 F).
• Set Condition:
After a calibrated amount of cool down time the TIPM compares the ECT Sensor, IAT Sensor, and the Ambient Air Temp Sensor values.
Possible Causes
(G31) AAT SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
(G31) AAT SIGNAL CIRCUIT OPEN
(G930) AAT RETURN CIRCUIT OPEN
(G31) AAT SIGNAL CIRCUIT SHORTED TO GROUND
(G31) AAT SIGNAL CIRCUIT SHORTED TO THE
(G930) AAT RETURN CIRCUIT AMBIENT AIR TEMPERATURE SENSOR
TOTALLY INTEGRATED POWER MODULE

esi2004

Just for Edit and giggles I put a thermometer between the heated blanket and batteries this morning.

passenger side read 160 degs and the driver side read 170 degs!

That has to be way too hot.

xcc_rider

I think you called that one. You're probably cooking the water out of the batteries at those temps.

jhenson

I can already see chaikwa reaching for his hammer!!!!