Dear Doctor: My 2009 Toyota Camry with 199,600 miles has a check engine light showing the codes P0101 and P0170. I have already replaced the MAF sensor, PCV valve, throttle body, the car's computer, O2 sensors, cam sensor, crank sensor, fuel pump, injectors, and fuel pressure regulator. I also checked for multiple vacuum or air leaks, and the cabin air filter, spark plugs, alternator, and battery have all been checked over the course of a year. Now the car has both codes showing consistently and it shakes at idle. What should we do? — Cheyenne
Dear Cheyenne: The engine has a lean condition, or at least is telling the computer it is running lean. The first step is to find out when the computer set the fault code, the engine speed, and temperature and gas pedal position. The problem could be a faulty front air ratio sensor and rear 02 sensor -- and both always need replacement together. Identifix shows multiple trouble test details on these codes, and identified a repair diagnosis to one owner's car as the ground wire on the mass air flow sensor circuit.
Dear Doctor: The automatic transmission in my 2001 Isuzu Rodeo is locked in neutral. I parked in my driveway and when I went to use it a few days later it would not shift into gear. It is a sealed transmission. Could it be the transmission control module? Should I replace it? It has only 80,000 miles and is well maintained. — Pat
Dear Pat: Check the transmission linkage: Disconnect the shift linkage from the shift cable and see if the transmission is still locked up. I have seen range sensors lock up, and even rust on the shift level shaft can cause locking.
Dear Doctor: I own a 2009 Cadillac CTS. The temperature control on the dash has been replaced twice in the past six months. The serviceman does not know what is causing the problem or why it has broken twice. What can you advise me? — Glenn
Dear Glenn: There are no common symptoms, history, or bulletins on the problem you describe. I recommend you check the connections, including grounds first, followed by checking the blend door motors for movement.
Dear Doctor: I have a 2013 Cadillac XTS. The CUE touchscreen became unresponsive starting with a small area in one corner, and eventually spreading to the entire touchscreen. The dealer says the only fix GM can provide is replacement of the entire CUE module for $1,500. A number of aftermarket options are available to replace the touchscreen alone. I did explore having it worked on at an automotive audio shop that refused to install an aftermarket unit, offering to send the entire CUE module out to be repaired. What is my best option? — Bill
Dear Bill: At my shop we send all of our touchscreen issues out to a company that does all factory units. Contact United Radio East in Syracuse, N.Y. The other option is an aftermarket unit with the additional module for the steering hub controls.
Dear Doctor: I have a 2017 Honda CR-V with 6,500 miles. The dealer suggested I need to perform these services right now: change air filter, cabin filter, differential fluid, and brake flush. They quoted a price of $500. What can I do? I'm an 80-year-old woman with a fixed income. — Susan
Dear Susan: I suggest an oil change and tire rotation only. At 6,500 miles all fluids are still like new, as are the filters. You can go to any professional auto shop that employs ASE technicians for any service needed. Save your service receipts to keep the warranty in place.
— Junior Damato is an ASE-certified Master Technician. Email questions for publication to firstname.lastname@example.org. Mail questions to: Motor Matters, PO Box 3305, Wilmington, DE 19804.