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P0133 and P0171 Diagnosis for 1999 Dodge Dakota 4x4 with 83K Miles

Model: 1999 Dodge Dakota Fault Code: P0133 Posted: 2007-01-10 14:01

Hello everyone, great community here! My name is Brian, and I'm currently experiencing several issues with my 1999 Dodge Dakota. Vehicle Details: - Model: 1999 Dodge Dakota - Drive Type: 4x4 - Transmission: Automatic (AT) - Engine: 5.2L V8 - Mileage: Approximately 83,000 miles Symptoms Observed: - A strong smell of fuel richness is noticed early in the drive. - Severe hesitation occurs under acceleration. - Under heavy throttle, black smoke is emitted — not white or gray. - The Malfunction Indicator Lamp (MIL) activates shortly after these symptoms. - After resetting the engine control unit (ECU), the vehicle runs normally for about 20–25 miles before the issue returns. Diagnostic Codes: - P0133: Oxygen Sensor Circuit Slow Response (pre-cat sensor) - P0171: System Too Lean (or more accurately, system too rich — depending on interpretation; however, symptoms suggest a rich condition) Maintenance History: - The oxygen sensor before the catalytic converter has been replaced twice. The first replacement was at around 82K miles and was under warranty. It failed again after six months. - The post-catalyst oxygen sensor was replaced by me during the Christmas weekend due to urgency. I'm seeking advice on possible root causes, especially given the recurring nature of the P0133 code and the black smoke emission. Any insights would be greatly appreciated! Thanks, Brian

Related fault codes
P0133P0171
Comments (3)
Anonymous 2007-01-10 14:16

A common cause for both P0133 and P0171 in this vehicle is an exhaust leak upstream of the oxygen sensors or a wiring issue with either sensor. I recommend performing a backpressure test to ensure the catalytic converter isn't clogged or restricted, as this can affect air-fuel mixture readings.

Anonymous 2007-01-10 14:23

Exhaust leaks are also a likely culprit. I’ve done some research on this model before joining. The post-cat O2 sensor is Bosch; however, I don’t know what brand the shop used for the pre-cat sensor during its two prior replacements. I’ll ask them directly to confirm that detail. I’m hoping it’s not a wiring fault — that would be concerning and could lead to further misfires or emissions issues.

Anonymous 2007-01-10 16:55

Update: Upon returning home, I noticed a coolant smell. This suggests a possible water pump leak or a related component failure near the radiator. I’ll investigate this more thoroughly tonight and update with further findings if needed.