← Back to list

2001 Saturn L300 V6 with P0159, P0174, P0453: Rough Idle, Poor MPG, Black Smoke - What to Do Next?

Model: 2001 Saturn L300 V6 Fault Code: P0159 Posted: 2018-03-11 14:01

2001 Saturn L300 V6, 110,000 miles. Experiencing rough idle, poor fuel economy, and black smoke exiting the tailpipe. Recently replaced spark plugs, ignition coils, and EGR valve. Despite these repairs, persistent fault codes P0159, P0174, and P0453 remain. Should I replace the downstream oxygen sensor or test the catalytic converter? What is the most effective troubleshooting sequence for these specific codes?

Related fault codes
P0159P0174P0453
Comments (5)
Anonymous 2018-03-11 14:32

Start with code P0174. Refer to detailed causes and solutions available in this forum's trouble code section.

Anonymous 2018-03-11 16:22

I've reviewed all possible explanations thoroughly. I'm particularly curious about how these multiple codes interact with the observed symptoms like rough idle and poor fuel economy.

Anonymous 2018-03-11 21:31

Codes P0159 and P0453 are unlikely to be directly responsible for rough idle or poor fuel efficiency. Focus on resolving P0174 first. If you have a scan tool capable of reading engine parameters, that would allow more precise diagnostics. With such data, I can offer targeted advice. Possible symptoms associated with P0174 (rich mixture condition) include: lack of power, increased fuel consumption, detonation (spark knock), hesitation or surging during acceleration. Potential causes: - Dirty or faulty Mass Air Flow (MAF) sensor (if equipped) - Vacuum leak downstream of the MAF sensor - Fuel system issues (fuel rail, injectors, pump, regulator) Solutions: - Cleaning the MAF sensor often resolves the issue. Locate it in your service manual if needed. - Remove and clean with electronic or brake cleaner; avoid damaging the sensor. - Ensure it is completely dry before reinstallation. - Inspect all vacuum and PCV hoses—replace any that are cracked or loose. - Check fuel filter condition and verify proper fuel pressure. Read more: P0174 explanation

Anonymous 2018-03-12 06:49

Thank you. A repair shop has completed all work so far, but they appear to be guessing and replacing parts without clear diagnostics. Should I take the car to the dealer for a full diagnostic check to confirm or rule out faulty oxygen sensors or catalytic converter issues? Or should I let the mechanic replace the O2 sensors and hope it works? I've already spent $900—this is critical for my daughter's final semester of college. What’s the most cost-effective and reliable path forward?

Anonymous 2018-03-12 07:48

As a consumer, the best approach is to have the shop perform diagnostics and hold them accountable for any incorrect diagnosis or repair that fails to resolve the issue. Regarding the catalytic converter: there is no specific error code indicating a failure in the converter. P0453 relates to evaporative system leak detection, not catalytic converter performance. Therefore, it's unlikely that the cat converter is the root cause.