Question about Chrysler PT Cruiser

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O2 sensor heater p0031p0037

Replaced ecu and o2 sensors could this be a ground issue?

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  • Mike O'Larte
    Mike O'Larte Mar 31, 2014

    Follow up w/more info:

  • Mike O'Larte
    Mike O'Larte Mar 31, 2014

    2005 PT cruiser Limited 2.4L turbo. The o2 sensors were replaced with genuine chrysler parts.The heater voltage is ok during warm up (~12V). After warm up 12v shuts down and MIL throws P0031 & P0037 codes. Ground continuity good from PMU connector (orange pin 27) to chassis ground. Is it possible that the vehicle info, VIN, mileage,tire size, was not flashed correctly? I have read that incorrect mileage and tire size can throw codes. Otherwise I am stumped. BTW, the PMU is under warranty. They provided me with a replacement for the 2nd PMU. Same problen. I doubt that 2 in a row would be bad and throw the same codes.

  • Mike O'Larte
    Mike O'Larte Mar 31, 2014

    Is there an O2 sensor relay in this car? If so, where is it?



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  • Chrysler Master
  • 354 Answers

You have to check at the O2 sensor connectors that there is power and ground to the heater circuit. This will minimize you diagnostic time.

Posted on Mar 30, 2014


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Posted on Jan 02, 2017

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SOURCE: 2001 dodge durango 4.7liter 4x4 i replaced front

bank 1 sensor 2 is the left downstream sensor (1/2) is located in the exhaust downpipe just after the mini-catalytic convertor, and before the main catalytic convertor. Now the meaning of this is that your not getting any 12+/12- heating on sensor, which means voltage is supplied to heat sensor up. You have a O2 sensor heater relay, but not getting problem with 2/2 sensor tells me you need to check/inspect the wiring for 1/2 sensor, open wiring for 1/2 sensor and inspect

Posted on Feb 07, 2010

  • 21873 Answers

SOURCE: no ecu ground for o2 sensors

Year make and model ?

Posted on May 27, 2013

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Recently - asked about OBD2 code 0053. Advised to check heater fuse B1S1but none is listed in the care manual or diagrams. Both O2 sensor fuses are good... What next?

O2 sensor's don't have a fuse , except for the heater circuit. PCM - engine computer supply's five volt's , signal return and ground . All are connected at the PCM . The fuse's you are calling O2 sensor fuse's are for the heater circuit . The PCM controls the O2 heater circuit by pulse width modulation ,do you know what that is .There is a transistor inside the PCM that toggles the ground on an off to control the heater circuit . Unless you know automotive electrical circuit testing an testing PCM input's an outputs ,your best bet , take your vehicle to a qualified repair shop .

Pulse width modulation Pulse width modulation

Oct 25, 2017 | Cars & Trucks


How to make your own O2 Sensor Simulator!

What is an O2 sensor simulator?
The OBD-II cars (1996-1998) have two O2 sensors to measure the amount of oxygen in the exhaust gas. First sensor is measuring it right after gases escape engine and this data is used to adjust fuel trim of the engine, as well as catch some faulty conditions. The second sensor is located after the catalic converter, and is used to detect the health of catalic converter. The ECU expects the signal from the sensor to be oscillating from below 0.4v to above 0.6v, but not above 1.2v, every few seconds while driving.

If you install an aftermarket downpipe with no cat (which is for off-road applications only) the ECU will detect this and indicate an error (MIL). The You can reset the ECU to clear the error code.

How to build Your Own Oxygen Sensor Simulator!
The rest of the page shows how to build an oscillating signal generator with just the right frequency and voltage to fool the ECU. It is based on classical astable operating mode of 555 timer.

Don't attach it directly to the ECU right after assembly. Instead attach it to the battery and check the output. You should get approximately 0v/0.7v flipping about every 3.3 seconds when the car is not running, and 0v/0.9v when the car is running. The current should stay below 10mA.

One LED should be always on whenever the power is supplied. Another LED indicates when the output signal is high, so it should go on and off with the signal.

When tapping the ECU wires, check everything before hooking up the oscillator. The power source should read 0v when the key is removed, about 12.6v when they key is at ACC and about 14.3 when the alternator is running. The resistance between ground wire and the body shield of the ECU should be 0 ohms. And it would be best if you run the car and monitor the voltage of the original oxygen sensor wire before cutting it to make sure you have indeed got the right one. The resistance between ECU PIN #47 and ground is about 1.3 to 1.6 M Ohm.

The original sensor should still be dangling around, or plugged into the downpipe. The reason is that ECU also monitors the resistance of heater circuit inside the sensor. If you want to COMPELTELY disconnect it, you will need to measure the resistance of the heater circuit and install the right resistor between ECU PIN #72 and ECU PIN #31 Anyway, there is no need to do it if you just leave O2 sensor alone and only intercept the oxygen signal wire.

R1 100 K Ohm
R2 1 M Ohm
R3 100 K Ohm
R4 10 K Ohm
C1 4.7 uF
C2 22 uF
D1 1.7v@20mA LED
D2 1.7v@20mA LED
I assume no responsibility for any kind of damages.

on Jul 10, 2010 | Mitsubishi Eclipse Cars & Trucks

2 Answers

Can brain box make oxygen sensor malfunction?

if you mean the ecu. then no, O2 sensor has a heater built into the sensor this preheats the sensor to read the O2 measurements if the heater fails it will read a fault and the ecu will give out a code. it will also give out the same code or different code if the sensor has failed. this is no repairable unit, sometimes it can be the connection from the sensor to main wiring, the plug seal can go and let water into the socket this would make the sensor appear faild to the ecu. if this is the case replace the seal and clean the connections.

Jul 06, 2017 | Cars & Trucks

1 Answer

My 96 prelude keeps shutting off when hot. What do I do to fix it?

96's are kinda the bad year for our cars being the only obd2 4th gen preludes so for any codes over 43 you have to look it up in the '97-'01 manual. Code 65 is "Secondary Heated Oxygen Sensor Heater Circuit Malfunction (Sensor 2)". Probable causes are an open in the secondary O2 sensor heater circuit or bad ECU. Have you tried resetting the ECU to see if it comes back? If so, you could check for loose wires coming from the secondary O2 sensor in the cat converter going to the 4 pin connector, or if you have access to another ECU I would try to substitute a known good ECU to see if that clears it up. The troubleshooting flowchart is on page 11-79 in the '97-'01 helms manual, and involves checking resistances and for continuity.

I think this could be the code I had on my '96 when I bought it. I tried replacing the secondary O2 sensor, and long story short it was the ECU. Luckily my '96 was still under the extended emmissions warranty, so Honda replaced it for free. I don't think you would be covered under the extended warranty because it was 14 years and under 150k miles. I just barely made it (within a month or 2 and 3k miles) last year.

As far as the engine sounds and rough idle, you could just need a valve adjustment. The secondary O2 sensor just checks the cat to make sure it's working right.

And all auto trans want to move forward when the brake is released.

Aug 02, 2015 | 1996 Honda Prelude

1 Answer


Well this wasn't what I expected to hear. Your car is only two years old. My first question is, Isn't this car still under warranty? To get back to your request, P0050: The ECU detected that the upstream O2 sensor heater failed. The heating element is inside the O2 sensor and when the car's ECU decides that it wants to turn the heat on, it closes the ground inside itself. Without diagnostic equipment you are not going to find out what failed. there are only four possible causes. The wiring to the O2 sensor is damaged, The fuse to the O2 sensor has blown, The O2 sensor is broken, or the ECU is partially damaged. Well I hope this helps. If you have any other questions please ask away. Be detailed so I can help you better, good luck.

Mar 03, 2014 | 2012 Hyundai Accent GLS Sedan 1.6L 4-cyl....

1 Answer

No ecu ground for o2 sensors

Year make and model ?

May 27, 2013 | Cars & Trucks

2 Answers

2004 pontiac vibe. both o2 sensors have been replaced and the code was cleared. engine lite came back on. its saying p0042 bank1. what else can it be.

There is 2 system in O2 sensor one is the sensor itself
and the other one is the heater
the code you have means the heater is not working look for the fuse or find out why heater is not working
don't put any anti seize lubricant on O2 sensor no ground for heater
hope it help

Jan 17, 2013 | 2004 Pontiac Vibe

2 Answers

Replaced both O2 sensors and still getting check engine light code 0135 what to do next?

Have you disconnected, and reconnected the vehicle battery yet? If you do not have a scanner, you need to do this-otherwise, the ECU will reset itself after a few drive cycles if the issue is resolved. Leave it disconnected for a few minutes, then hook it back up and let it idle for a few minutes, then gently drive it for another 5-10 minutes. If that does not fix it, here are reasons for your continuing problem:O2 Heater element resistance is high, Internal short or open in the heater element, O2 heater circuit wiring high resistance, or open or short to ground in the wiring harness. Since your sensors are new, your problem is either in the connectors or wiring-examine then for breaks or cracks, and using a meter check to see if you have good reference voltage, and especially power (12 volts).

Jul 19, 2011 | 1999 Acura CL

4 Answers

Engine light poo38

That is the oxygen sensor on bank 1 down by the cat converter.

Oct 21, 2009 | 2004 Jeep Liberty

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