PO150 and PO325 Error Codes on 1996 Nissan Maxima GLE: Causes, Fixes, and Repair Cost Guide

You could try replacing both the oxygen (O2) sensor and the knock sensor yourself as a first step—this might resolve the PO150 and PO325 codes. However, if the issue persists, you’ll have spent the cost of the parts plus your own time. I don’t offer sympathy for mechanics charging $400 just to diagnose a problem. I face this every day with customers who want part replacements without understanding diagnostics. The only situation where you deserve credit or compensation is when a mechanic guarantees a fix and it fails. But I’ve seen too many cases where customers pay $400+ for a simple broken wire in a sensor circuit—something that was already replaced by another mechanic or the customer themselves. If you’re technically skilled, invest in diagnostic tools to test the circuits of both sensors. This will help determine whether replacement is truly necessary. If this isn’t practical, then it’s likely why such high fees exist. Remember: a shop's posted rate of $90 per hour doesn't mean mechanics are paid that—those rates cover overhead. If you think mechanics are expensive, check out plumbers or electricians—they often charge more and travel with full toolkits. That said, this is another topic for another time. Best of luck, and please update us on your progress! Jeff

Jeff wrote: You could try replacing both the oxygen (O2) sensor and the knock sensor yourself as a first step—this might resolve the PO150 and PO325 codes. However, if the issue persists, you’ll have spent the cost of the parts plus your own time. I don’t offer sympathy for mechanics charging $400 just to diagnose a problem. I face this every day with customers who want part replacements without understanding diagnostics. The only situation where you deserve credit or compensation is when a mechanic guarantees a fix and it fails. But I’ve seen too many cases where customers pay $400+ for a simple broken wire in a sensor circuit—something that was already replaced by another mechanic or the customer themselves. If you’re technically skilled, invest in diagnostic tools to test the circuits of both sensors. This will help determine whether replacement is truly necessary. If this isn’t practical, then it’s likely why such high fees exist. Remember: a shop's posted rate of $90 per hour doesn't mean mechanics are paid that—those rates cover overhead. If you think mechanics are expensive, check out plumbers or electricians—they often charge more and travel with full toolkits. That said, this is another topic for another time. Best of luck, and please update us on your progress! Jeff I hear you—your point hits home. My husband is a video editor, and all he sells is his time and expertise. I’d have lots of pennies if I had one for every client who thought an edit was 'simple.' But $400? That’s way too much for just 'looking around' at $85 per hour—especially with a flat rate. If the technician finds the root cause in 30 minutes, why isn’t there a pro-rated fee? After some research, I found a dealership offering a one-hour diagnostic that's credited toward repair costs. While parts may be slightly more expensive from them, overall it’s better than paying $400 for a 'looksee.' Thanks for the insight! Alli

Let me know how your troubleshooting goes—I’d love to hear what you find out!