2018 Toyota Yaris

The 4-speed automatic transmission in the 2015 Yaris can develop harsh and delayed shifts, particularly the 2-3 upshift and the 3-2 downshift. The transmission may also slip or shudder during light acceleration. Fluid degradation and worn solenoids are common contributing factors at higher mileages.

Perform a transmission fluid drain and refill with Toyota Type T-IV automatic transmission fluid. If shifting issues persist after a fluid change, the transmission solenoid pack may need replacement. A full transmission rebuild or replacement may be necessary in severe cases with slipping.

The A/C compressor on the 2015 Yaris (1.5L 1NZ-FE engine) is prone to premature clutch bearing failure and internal compressor damage. Owners notice a squealing noise from the engine bay when the A/C is engaged, followed by the system blowing warm air. Complete compressor seizure can also damage the serpentine belt.

Replace the A/C compressor and clutch assembly, receiver-dryer, and expansion valve. A full system flush is required if the compressor shed metal debris. Use only the specified ND-OIL 8 compressor oil and R-134a refrigerant. Inspect the serpentine belt for damage caused by compressor seizure.

Some 2015 Yaris models experience intermittent electrical issues including parasitic battery drain, flickering dashboard lights, and intermittent power window failures. The vehicle may fail to start after sitting for 2-3 days due to a dead battery. Common causes include a faulty door courtesy light switch and aftermarket accessories improperly wired.

Perform a parasitic draw test to isolate the circuit causing the drain. Common culprits include the interior courtesy light switch in the driver door jamb and the radio head unit not entering sleep mode. Replacing the battery with a higher CCA-rated unit can mask the symptom but does not fix the root cause.

The rear drum brakes on the Yaris are prone to groaning, squealing, and grabbing, especially in humid conditions or after the vehicle sits overnight. The automatic adjuster mechanism may fail to keep the shoes properly adjusted, causing a low brake pedal and increased stopping distances.

Remove the rear drums and inspect the brake shoes, hardware, and adjuster mechanism. Clean the drum contact surfaces and replace the adjuster hardware kit. Apply brake grease to the shoe contact points on the backing plate. Replace the shoes if they are glazed or contaminated with brake dust.

The electric power steering on the 2015 Yaris may feel noticeably heavier or provide reduced assist during cold starts in freezing temperatures. The steering gradually returns to normal as the vehicle warms up, but the initial minutes of driving can require significantly more steering effort. The EPS control unit calibration is the root cause.

Toyota has not issued a formal TSB for this behavior. The EPS system is designed to reduce assist when the control unit detects low temperature to protect internal components. Allowing the vehicle to idle for 1-2 minutes before driving in extreme cold can reduce the effect. An EPS control unit software update may be available at the dealer.