Engine Diagnostics

A U-type diagnostic trouble code (DTC) indicates a problem with the A. engine or transmission.B. body.C. chassis.D. network.2. Technician A says that generic scan tools must be able to read all generic OBD-II codes. Technician B says that all generic scan tools must be able to read manufacturer OBD-II trouble codes. Who is correct? A. Technician AB. Technician BC. Both Technicians A and BD. Neither Technician A nor B3. A vehicle fails an HC emission test at idle and 2,500 rpm, and the engine has an acceleration stumble. The heated oxygen sensor (HO2S) voltage is 0.1–0.3 volts on a scan tool, and the injector pulse width is high. No diagnostic trouble codes (DTCs) are found. When propane is directed into the air intake, HO2S voltage immediately increases and the injector pulse width decreases. The mostlikely cause of this problem is A. low fuel-pump pressure.B. an opening in the O2 sensor signal wire.C. a defective O2 sensor.D. a defective powertrain control module (PCM).4. Technician A says that a new replacement part is always good. Technician B says that sometimes recent repair work will be the cause of a complaint. Who is correct? A. Neither Technician A nor BB. Technician AC. Both Technicians A and BD. Technician B5. The first character of a diagnostic trouble code (DTC) indicates the vehicle system. Which one of the letters below refers to the chassis and transfer cases? A. PB. UC. CD. B6. Technician A says that OBD-II systems include generic as well as vehicle manufacturer’s specific diagnostic trouble codes (DTCs) and scan data displays. Technician B says that OBD-II systems have common DTCs. Who is correct? A. Technician BB. Both Technicians A and BC. Neither Technician A nor BD. Technician A7. An OBD-II system interprets a disconnected spark plug as a misfire that could damage the three-way catalyst. The ECM or PCM will most likely trigger the malfunction indicator lamp (MIL) on the _______ trip. A. thirdB. secondC. firstD. fourth9. Which of the following is least likely checked by the comprehensive component monitor? A. OpensB. RationalityC. Shorts-to-powerD. Shorts-to-ground12. Technician A says that nonemission-related codes that make the malfunction indicator lamp (MIL) illuminate are called “Type A” codes. Technician B says that emission-related codes that illuminate the MIL after the first fault are called “Type A” codes. Who is correct? A. Technician BB. Neither Technician A nor BC. Technician AD. Both Technicians A and B13. What OBD-II term applies when all enabling standards for a specific diagnostic trouble code (DTC) are met? A. Trip criteriaB. Warmed-up engineC. Well-tuned engineD. Freeze frame14. Technician A says that the last step in the diagnostic process is to verify the problem. Technician B says that the second step is to perform a thorough visual inspection. Who is correct? A. Technician BB. Both Technicians A and BC. Technician AD. Neither Technician A nor B15. All of these concerns can be diagnosed using the paper test except for a A. cracked exhaust manifold.B. bad spark plug wire in the ignition system.C. burned valve.D. faulty injector on a multiport engine.16. The powertrain control module (PCM) or engine control module (ECM) will automatically clear a diagnostic trouble code (DTC) if there are no additional faults detected after A. the criteria to clear codes is reached.B. two consecutive trips.C. eighty warm-up cycles.D. five key-on/key-off cycles.17. Technician A says that when the malfunction indicator light (MIL) or service engine light is on, you should retrieve the diagnostic trouble code (DTC) and follow the manufacturer’s recommended procedure. Technician B says that all OBD-II monitors must have the enable criteria achieved before a test is performed. Who is correct? A. Technician BB. Both Technicians A and BC. Technician AD. Neither Technician A nor B18. Technician A says that a cracked exhaust manifold can affect oxygen sensor operation. Technician B says that a clogged air filter element won’t affect emissions. Who is correct? A. Both Technicians A and BB. Neither Technician A nor BC. Technician BD. Technician A19. Which of the following is not a condition under which the malfunction indicator light (MIL) or service engine light is turned off? A. DTCs are cleared by a scan toolB. Criteria for the PCM to clear codes is reachedC. Powertrain control module (PCM) link is groundedD. Vehicle battery is disconnected20. All of the following items are important to know when diagnosing an engine drivability problem except for the A. list of previous repairs.B. brand of engine oil used.C. type of gasoline used.D. temperature of the engine when the problem occurs.