OBD-II Code

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performance fault diagnosis guide

P2404 Code: EVAP Leak Detection Pump Sense Circuit Range/Performance

P2404 is the OBD-II code for an EVAP Leak Detection Pump Sense Circuit fault — a signal problem at the pump that tests for leaks, not an actual leak. Often the pump, wiring, or ECM...
P0410 Code: The Cold-Start Air Pump Isn't Doing Its Job

P0410 Code: The Cold-Start Air Pump Isn't Doing Its Job

P0410 is the OBD-II code for a Secondary Air Injection System fault — the cold-start emissions pump that isn't working. Most cases are a moisture-damaged pump or carbon-clogged valve, fixable DIY.
P0232 Code: Check the Fuel Pump Relay Before the Pump Itself

P0232 Code: Check the Fuel Pump Relay Before the Pump Itself

P0232 = Fuel Pump Secondary Circuit High. The pump won't shut off after key-off, hard starts, stalls. 40-50% are a $15 stuck relay — listen by the tank to diagnose for free in 10 seconds.
P3497 Code: Check Your Oil Dipstick Before Anything Else

P3497 Code: Check Your Oil Dipstick Before Anything Else

STOP — Check Your Oil Dipstick Before Buying Any Parts. P3497 Code: Check Your Oil Dipstick Before Anything Else P3497 is the OBD-II code where about 50% of cases are solved in 5 minutes by...
P0315 Code: Run the Relearn Before Buying Any Crank Sensor

P0315 Code: Run the Relearn Before Buying Any Crank Sensor

STOP — A Scanner Command Often Fixes This Code. Don't Replace Parts First. P0315 Code: Run the Relearn Before Buying Any Crank Sensor P0315 is the OBD-II code most likely to result in unnecessary parts...
P1299 Code: Engine in Limp Mode? Suspect the CHT Sensor First

P1299 Code: Engine in Limp Mode? Suspect the CHT Sensor First

STOP — Never Assume P1299 Is Just the Sensor Without Verifying Actual Temperature. P1299 Code: Engine in Limp Mode? Suspect the CHT Sensor First P1299 is one of the most "panic-inducing" Ford codes — your...
P0523 Code: Sensor Says High Oil Pressure — Use a Gauge to Verify

P0523 Code: Sensor Says High Oil Pressure — Use a Gauge to Verify

STOP — Never Replace the Sensor Until You Verify with a Mechanical Gauge. P0523 Code: Sensor Says High Oil Pressure — Use a Gauge to Verify P0523 is one of the most safety-critical OBD-II codes...
U0401 Code: Invalid Data on the CAN Bus, Not a Failed PCM

U0401 Code: Invalid Data on the CAN Bus, Not a Failed PCM

STOP — Don't Replace Your ECM Until You've Tested Pins 6 and 14. U0401 Code: Invalid Data on the CAN Bus, Not a Failed PCM U0401 is one of the easiest OBD-II codes to misdiagnose....
P0607 Code: Before You Replace the PCM, Test These 4 Things

P0607 Code: Before You Replace the PCM, Test These 4 Things

STOP — Don't Authorize a $1,500 PCM Replacement Without Reading This. P0607 Code: Before You Replace the PCM, Test These 4 Things P0607 is the OBD-II code shops love most — it says "PCM performance...