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99 Dodge Dakota 3.9L Engine Stalls When Warm: P0132 O2 Sensor Issue and Heater Circuit Diagnosis

Model: 99 Dodge Dakota Fault Code: P0132 Posted: 2016-11-12 18:21

My 1999 Dodge Dakota with a 3.9L engine runs smoothly when cold but begins to stall or slow down significantly as it warms up. It frequently exhibits hesitation, nearly dies, then briefly recovers before repeating the cycle. I used a CarMD scanner and initially detected codes P0133 and P0135. After disconnecting the battery cable and holding the key in the start position for 15 seconds, I cleared the codes. However, after driving the vehicle, the same issue returned and the scanner showed code P0132. I disconnected the front O2 sensor (which was previously removed) and measured voltage on pin 1 of its harness connector — reading 4.22 volts with the key on but engine off. The sensor has a four-wire connector, and I'm unsure if this is the correct wiring configuration or whether there's an issue with the heater circuit. The truck originally ran well for over 10 years without issues. Now, drivability is severely affected. I've confirmed that pin 1 corresponds to the DG/PK wire (positive), but voltage is only around 4V when ignition is on and engine off. No ground issues have been found so far. I’ve also noted that the OBD-II display shows M,F,CC as solid and C,O,OH as blinking — possibly indicating emission monitor status. However, I cannot load CarMD software onto my PC to interpret these codes fully. After disconnecting the front O2 sensor, I drove the vehicle for a distance and it ran normally without stalling. I did not clear the P0132 code from the ECU or reconnect the battery. The question remains: is it safe to operate the truck permanently with this sensor disconnected? Are there any known fixes or diagnostics for this specific P0132 issue on a 1999 Dodge Dakota 3.9L?

Related fault codes

P0132

Comments (6)

Anonymous 2016-11-12 21:08

P0132 is likely not the root cause of drivability issues — it's more related to the oxygen sensor heater circuit than engine performance. Please confirm that pin 1 on the O2 sensor connector is connected to the DG/PK wire (positive). The expected voltage should be close to 12V when the ignition is on and engine off. Check for proper grounding as well — a poor ground can cause erratic readings. The heater circuit for both O2 sensors is powered by fuse A in the Power Distribution Center (PDC). Are there any other diagnostic codes present? Any additional symptoms? Reference: http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=16322

Anonymous 2016-11-16 16:38

No other fault codes are present. The drivability issue is very real and directly impacts daily use. Voltage at pin 1 (DG/PK) is only 4.22V when the key is on but engine off — not 12V as expected. I’ve checked for ground connections, and no issues found. However, I suspect a wiring or sensor heater circuit fault. I re-scanned the vehicle and still see P0132. The OBD display shows M,F,CC as solid (complete) and C,O,OH as blinking (incomplete). Since my PC cannot load CarMD software, I don’t know what these letter groups mean — but they may indicate emission system status. I’ve confirmed there is only one O2 sensor located ahead of the original exhaust cat. After disconnecting that sensor, the truck ran fine during a test drive.

Anonymous 2016-11-17 10:06

Please confirm: is pin 1 indeed connected to the DG/PK wire? Ensure you're referencing the correct wiring diagram. With the front O2 sensor disconnected — what voltage do you read on the DG/PK wire at pin 1? The M,F,CC and C,O,OH groups are likely emission monitors. Solid indicators may mean complete monitoring, flashing ones indicate incomplete or failed checks. These can be a secondary concern for now but should be monitored.

Anonymous 2016-11-24 17:39

Pin assignments: 1=green/pink, 2=black, 3=black/blue, 4=orange/grey. When running: pin 3 to 4 reads 3.98V; when not running (ignition on), pins 1 to 2 show no voltage. At startup: initial voltage at pins 1 to 2 was 14.52V, then dropped to 0.26V as engine warmed up. Only one O2 sensor is installed ahead of the original catalytic converter location. After disconnecting the front O2 sensor and driving, the truck ran smoothly without stalling. I did not clear the P0132 code or disconnect the battery. Is it safe to operate this way long-term? Any suggestions on how to resolve the underlying issue? I have not replaced the front O2 sensor.

Anonymous 2016-11-24 17:54

Is there supposed to be voltage between pins 1 and 2 (with pin 1 as positive and pin 2 as ground)? During my last test, no voltage was detected at pins 1 to 2 when the ignition was on but engine off. Could this voltage drop during startup be due to alternator output? If so, why did it disappear after warm-up? I’ve inspected all wiring and confirmed the PCM connectors are intact. No visible damage or loose connections.

Anonymous 2016-11-25 10:57

Full diagnostic details available here: http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=16322