Fuel And Emissions Systems

Symptom Troubleshooting Index

When the vehicle has one of these symptoms, check for a diagnostic trouble code (DTC) with the HDS. If there is no DTC, do the diagnostic procedure for the symptom, in the sequence listed, until you find the cause.

Symptom	Diagnostic procedure	Also check for
Engine will not start (MIL works OK, no DTCs set)	Troubleshoot: Engine Will Not Start, Engine Starts But Stalls Immediately, or Engine Is Hard To Start .
Engine will not start and HDS does not communicate with the PCM (MIL comes on and stays on, no DTCs set)	PCM power and ground circuit troubleshooting - Refer to: PCM Power and Ground Circuit Troubleshooting or PCM Power and Ground Circuit Troubleshooting (2019 2020 2021)
MIL comes on and stays on, or never comes on at all, no DTCs set	Troubleshoot the MIL circuit - Refer to: MIL Circuit Troubleshooting or MIL Circuit Troubleshooting (2019 2020 2021)
Engine will not start (MIL works OK, no DTCs set, immobilizer indicator stays on or flashes)	Check the immobilizer system - Refer to: Keyless Access System Symptom Troubleshooting Information (2016 2017 2018) or Keyless Access System Symptom Troubleshooting Information (2019 2020 2021)
Engine starts but stalls immediately (MIL works OK, no DTCs set, immobilizer indicator stays on or flashes)	Check the immobilizer system - Refer to: Keyless Access System Symptom Troubleshooting Information (2016 2017 2018) or Keyless Access System Symptom Troubleshooting Information (2019 2020 2021)
Engine is hard to start (MIL works OK, no DTCs set)	Troubleshoot: Engine Will Not Start, Engine Starts But Stalls Immediately, or Engine Is Hard To Start .
Cold fast idle too low (MIL works OK, no DTCs set)	1. Do the PCM Idle Learn Procedure . 2. Check the Idle Speed Inspection . 3. Do the Throttle Body Carbon Accumulation Check .
Cold fast idle too high (MIL works OK, no DTCs set)	1. Do the PCM Idle Learn Procedure . 2. Check the Idle Speed Inspection .	Intake air leaks
Idle speed fluctuates (MIL works OK, no DTCs set)	1. Do the PCM Idle Learn Procedure . 2. Check the Idle Speed Inspection . 3. Do the Throttle Body Carbon Accumulation Check . 4. Troubleshoot the A/C signal circuit - Refer to: A/C Signal Circuit Troubleshooting, or A/C Signal Circuit Troubleshooting (2019 2020 2021) 5. Check the A/C refrigerant amount - Refer to: A/C Refrigerant Recovery/Evacuation/Charging (134a) or A/C Refrigerant Recovery/Evacuation/Charging (1234yf) NOTE: Turning the A/C to ON under the conditions that the A/C refrigerant amount is out of specification (excessive or too little) may cause the idle speed fluctuation.	Incorrect valve adjustment Intake air leaks
After warming up, idle speed is below specifications without load (MIL works OK, no DTCs set)	Do the Throttle Body Carbon Accumulation Check .	Incorrect valve timing or clearance adjustment
After warming up, idle speed is above specifications without load (MIL works OK, no DTCs set)	Inspect the APP sensor .	Intake air leaks
Low power (MIL works OK, no DTCs set)	1. Check The Fuel Pressure . 2. Check the Air Cleaner Element - Removal, Installation, and Inspection .	Low compression Incorrect camshaft timing Incorrect engine oil level Exhaust restriction Fuel contamination
Engine stalls (MIL works OK, no DTCs set)	Troubleshoot: Fuel and Emissions Systems Symptom Troubleshooting - Engine stalls .
Difficult to refuel (MIL works OK, no DTCs set)	1. Check the fuel vent tube between the EVAP canister and the fuel tank. 2. Check the fuel tank vapor recirculation tube between the fuel fill pipe and the fuel tank. 3. Insert the emergency fuel funnel into the fuel filler neck, then check the operation of the primary shut-off valve flap. NOTE: The emergency fuel funnel is stored in the cargo tool box. 4. Replace the Fuel Tank - Removal and Installation .	Malfunctioning gas station filling nozzle
Fuel overflows during refueling (No DTCs set)	Fuel Tank - Removal and Installation .	Malfunctioning gas station filling nozzle
With auto idle stop system: Vehicle rolls backward when starting on the steep hill (MIL works OK, no DTCs set)	Do the VSA sensor neutral position memorization .
HDS does not communicate with the PCM or the vehicle	Troubleshoot the DLC circuit - Refer to: DLC Circuit Troubleshooting (2016 2017 2018) or DLC Circuit Troubleshooting (With CAN Gateway) (2019 2020 2021) or DLC Circuit Troubleshooting (Without CAN Gateway) (2019 2020 2021) .	Correct HDS software