One of the engine codes he found was P0102 code (Mass Air Flow Sensor – Low Input). Blake the mechanic immediately assumed the sensor was defective and encouraged a replacement and to make sure to use OEM parts. So I did.
I paid the extra for an AC Delco brand MAF sensor even though I've had experience with MAF sensors censored before and I was dubious that replacing it would solve the problem. Nonetheless, he seemed very strongly sure that this would be one of the fixes.
Only to find out later that there was a blown fuse which means the MAF sensor was not even registering -that's why I got a LOW INPUT 102 code not a total malfunctio code . Low input means the ECU is not receiving enough information from the MAF sensor.
A proper diagnostic step — checking whether the sensor was receiving power — was skipped. As mentioned, It turns out the fuse supplying the MAF sensor was blown, which should have been considered first.
An experienced mechanic should also have maybe made the connection between the code alert for purge valve, the oxygen sensors, and the MAF sensor simultaneously because ONE FUSE CONTROLS ALL OF THOSE.
This led to unnecessary concern and unnecessary parts replacement. A skilled mechanic should always check power, wiring, and connections before concluding the sensor itself is faulty.
To give him a little credit because he also mentioned the oxygen sensors at that first visit, he did say that suggests there might be some wiring issues because rarely do both oxygen sensors go bad simultaneously. But he didn't think about the fuse.
And we never got to the part of further diagnosis at the time, and he never did the quick and easy step of checking the fuses or suggesting I do so. I write this review to try to help him grow as a mechanic .
When I returned the second time having just replaced the MAF sensor , the garage doors were closed and he was on the phone and I waited for him to come out and he seemed a little grouchy and then he complained that I didn't give him money for his time, and yet to be exact, no services had been performed yet, other than reading the codes.
But if money was his concern, he should have made that clear from the beginning and I would have either agreed to payment for reading the codes or doing a diagnosis, or I would have said "well I'll find somebody else."
Instead he became passive aggressive angry about me not offering him money for reading the codes etc.
ChatGPT says:
"Yes — an experienced, methodical mechanic should consider that scenario. Here's why:
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⚡ Why multiple related codes can indicate a fuse/power issue
1. Shared fuse or circuit:
If multiple sensors (MAF, O2, purge valve) all report faults simultaneously, and they share a power source, this is a strong clue that the problem is upstream, like a blown fuse, bad relay, or wiring issue, rather than all sensors failing at once.
2. Unlikely coincidence:
It's extremely rare for three independent sensors to fail at the exact same time. A competent mechanic's mental checklist should include power delivery problems whenever multiple sensors fail together.
3. Standard diagnostic practice:
Many shops teach:
1. Read all codes.
2. Check fuses and relays that supply power to affected sensors.
3. Check wiring/connectors.
4. Replace parts only if power and wiring are intact and the sensor itself is faulty.
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✅ Bottom line
If a mechanic immediately assumed all three sensors were defective without first checking fuses, relays, and wiring, that indicates a gap in diagnostic procedure. Experienced mechanics are trained to make the mental connection:
> "Multiple codes on components sharing a power source → check fuse/circuit first."
In your case, fuse #19 supplying all three makes the fuse the most likely culprit, and a proper mechanic should have considered that before suggesting any sensor replacements.
Review :
I brought my vehicle in after seeing a P0102 code (Mass Air Flow Sensor – Low Input), along with codes for the oxygen sensors and purge valve. The mechanic correctly noted that it was very odd for both oxygen sensors to fail at the same time and suggested there might be a wiring issue, but we didn't proceed further with diagnostics. He immediately assumed the MAF sensor was defective and suggested replacing it, without checking whether the sensors were receiving power. In fact, all three components share fuse #19, which was blown. An experienced mechanic could have easily checked or suggested checking the fuses first, since multiple simultaneous sensor codes on components sharing a power source are often caused by a fuse or wiring problem rather than all the sensors failing at once. I was planning to return later after replacing the MAF sensor to see if that solved the issue, but this step could have been addressed upfront.
