VIN: 2HKRM4H7XK LWB - 127,430 mi - 2.4L I-VTEC
| Code | Description | Severity | Live Data |
|---|---|---|---|
| P0420 | Catalyst System Efficiency Below Threshold (Bank 1) | critical | 0.82V / 0.18V |
| P0171 | System Too Lean (Bank 1) | pending | STFT +12.4% |
| P0300 | Random/Multiple Cylinder Misfire Detected | critical | Misfire 8.2% |
| P0128 | Coolant Thermostat Below Regulating Temp | pending | CT 168F (target 195F) |
Downstream O2 sensor (B1S2) has failed - stuck at 0.18V instead of oscillating 0.1-0.9V. ECM interprets this as catalyst inefficiency, triggering P0420. Lean condition (P0171) is a secondary symptom: ECM overcorrects fuel trims trying to compensate for the bad catalyst reading.
P0300 misfire is related - lean mixture causes erratic combustion across cylinders. Once O2 sensor and catalyst are addressed, misfires should resolve.
Not a catalytic converter replacement. Not a transmission issue. Not a $2,800 job.
Replace downstream O2 sensor (B1S2)
Denso 234-4408 - 20 min
Clear codes, verify catalyst efficiency reset
Scan tool session - 10 min
Test-drive, confirm MIL off at 15+ min
Fuel for test - 25 min
Engine RPM
750RPM
Coolant Temp
168F
Short Term Fuel Trim
+12.4%
Long Term Fuel Trim
+8.1%
O2 Sensor B1S1
0.82V
O2 Sensor B1S2
0.18V
MAP Vacuum
18inHg
Battery Voltage
14.2V
A $40 code reader tells you what happened. Our factory tools show you why — with waveform proof.
Erratic spikes, signal dropout, inconsistent waveform — a dying injector washing the cylinder with fuel.
Clean sine wave, consistent amplitude, stable baseline — fault confirmed resolved after injector replacement.
Every report includes waveform evidence
No code reader. No guesswork. Just data.
Every finding comes with real data — oscilloscope waveforms, live sensor graphs, and evidence screenshots. No guesswork. No mystery.
Coil 4 — Oscilloscope CH1
Breakdown spike at 280V — coil failing under load
Consistent with P0304 misfire on cylinder 4
Every capture is timestamped, saved to your report, and available for review by any shop or insurer. This is your diagnostic data — not ours to interpret without you.
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We diagnose. You decide. Zero pressure to fix what isnt broken
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