Q: I own a 2012 Toyota Camry with the 2.5-liter engine. I have a problem in cold weather getting the engine to heat up to the center spot on the digital bar graph heat gauge. It moves up in three steps. It advances OK in Steps 1 and 2 but takes driving above 45 mph for several miles before it reaches the third step in the center. When I slow down to 35 mph the gauge will drop back down one step from center and stay there until I resume higher speed again. The dealer put in a new thermostat and said the coolant temp was reaching only 160 degrees. They said they installed a 170-degree thermostat, the warmest Toyota has. I checked parts stores and they have a 180-degree thermostat for my Camry. Do you think that would help? I am also getting very poor gas mileage, 22 to 26 mpg. I believe the engine is running in open loop most of the time because of not reaching normal operating temperature and staying there.
A: First, let's address the issue of whether or not the engine is running in open loop. Open loop is effectively the warm-up mode of operation, designed to bring the engine up to temperature as quickly and efficiently as possible. In open loop operation, the ECM reads only limited sensor data, typically the coolant sensor, mass airflow sensor, throttle position sensor, crankshaft position sensor and rpm. There is no oxygen sensor feedback to trim air/fuel ratios until the coolant reaches a specific temperature, at which point the system shifts into closed loop operation and uses all the sensor inputs to optimize air/fuel ratios.
Researching my ALLDATA automotive database, I find that if the system does not reach closed loop operation within roughly five minutes of start-up depending on ambient temperatures, the P0125 DTC fault code will be triggered. Similar DTCs — P0115, P0117 and P0118 — will cause the ECM to operate in the "fail-safe" mode and assumes the coolant temperature is 176 degrees. With this information, a simple 20-plus-minute idle warm-up and a scan tool should be able to detect if the system is operating in closed loop. And remember, mileage will certainly drop in cold weather due to the longer warm-up time each time the vehicle is started. By the way, according to my info the standard thermostat on your Camry begins opening at 176 degrees and is fully open by 183 degrees — effectively a 180-degree thermostat.
Now to the practical. Does the heater deliver good cabin heat? Output air temperature should be 130-plus degrees. If it is, the system is operating normally and I wouldn't be concerned about the fluctuations in the gauge. In fact, if the heater keeps you warm and the car had a coolant temperature warning light rather than a gauge, you'd have no indication of a problem.
Q: I read the "Motoring Note" in your column regarding remote controls for starting car engines. I own a 2015 Kia Optima, purchased new with the factory remote control. There is no problem with locking and unlocking the doors but starting the engine is another story. When I park the car in a large parking lot away from other vehicles the engine will start with two clicks as it should. But when I park in my driveway or congested area the car will not start reliably with the remote. I think the problem is more than just cellphones — perhaps it is too many rooftop satellite dishes, wireless electronics and whatever the nearby airport has for electronics. Recently I returned the car to the dealer again to fix the remote control and of course it started just fine.
A: Black helicopters? Nasty neighbor? Probably not. Ask your dealer to check TSB 034 dated January 2012. It offers an updated DNA card and reprogramming for specific 2011/2012 Optima and Sorento remote start modules.
Paul Brand is the author of "How to Repair Your Car" and "How to Repair Your Truck and SUV," published by Motorbooks.