IAT and oxygen sensor on a 1994 BMW 740i

Hello Joe Hord and thank you for asking...

FUEL pump in the clear... That is IMPORTANT.

A bunch of things... but the smart money would be to beg,
borrow or BUY an ODB (diagnostic) reader...

SAVEs big money on TOTALLY POINTLESS guessing and TAMPERING that is likely to leave you with more TROUBLES than you started with (ending in pointless replacements of VERY
expensive OXYGEN-SENSORS... BECAUSE the "clown"
at the "auto-zone" says "hey Oxygen Sensors"...

Typically Oxygen Sensors (like THERMOMETERS) merely
report the NEWs...

Buying a new THERMOMETER is not going to get rid of a
COLD... (or the plague).

The real NEWS is likely a MUFFLER BAFFLE has come
loose or the CATALYTIC CONVERTER has given it's all...
and is now blocking the EXHAUST.

From what you describe... my memory of being round the
bend... That's my better guess:

I like guessing games as much as the next guy... but
INTRODUCING more troubles is more likely if you
take the EASTER-EGG approach.

Check to see if your local EXHAUST shop will do a
"FREE" diagnostic read...

Happy hunting!

Cautionary note: If you live (here) in California you want to play
Very CLOSE ATTENTION to those SMOG regulations...

Gubnor Nuisance may be busy right now... But sooner or later
(end of the world or not) you are going to get that SMOG test...

It would make me sad to think you have to do the SAME JOB
all over again .

Good luck: better skill.

code p 0030 refers to heated oxygen sensor (HO2S) 1 bank 1 -heater control-circuit malfunction
code p 0039 refers to turbo/super charger bypass valve , control circuit --range /performance problem===causes --wiring--- bypass valve
code p 74 refers to outside air temperature sensor--circuit intermittent===causes ---wiring---poor connection---out side air temp sensor---ECM
code p 0098 refers to intake air temp (IAT) sensor 2 --circuit high input===causes --wiring short to positive ---IAT sensor---ECM

first make a tune-up to your car and clean de codes if the problem continues you need change the oxygen sensor

P0140 BMW P0140 BMW - O2 Sensor Circuit Low Voltage Bank 1 Sensor 2



Possible causes - Faulty Rear Heated Oxygen Sensor Bank 1
- Rear Heated Oxygen Sensor Bank 1 harness is open or shorted
- Rear Heated Oxygen Sensor Bank 1 circuit poor electrical connection
- Inappropriate fuel pressure
- Faulty fuel injectors
- Intake air leaks may be faulty
- Exhaust gas leaks

Replacing the Rear Heated Oxygen Sensor Bank 1 usually takes care of the problem
http://engine-codes.com/p0140_bmw.html

The 1999 5.3 V8 engine had 4 oxygen sensors. There are two catalytic converters on this engine, one on the driver side of the engine, and one on the passenger side of the engine. This is important to know, as the number of oxygen sensors is directly related to the number of catalytic converters on the vehicle. Driver side is referred to as Bank 1, passenger side is referred to as Bank 2. This is very important to know when looking up replacement oxygen sensors. There is one oxygen sensor in front of, or before the catalytic converter, usually referred to as a pre-catalyst O2 sensor. There is also one behind, or after the catalytic converter, usually referred to as a post-catalyst oxygen sensor. So, you have two oxygen sensors on Bank 1, and two oxygen sensors on Bank 2, for a grand total of 4 oxygen sensors.

could be the blend door

service manual.
Code Description Possible Cause
0 ECU / ECU signal No signal to ECU
1 Oxygen sensor circuit Oxygen sensor or circuit, ECU
2 Oxygen sensor circuit Oxygen sensor or circuit, ECU
3 MAP sensor circuit Map sensor circuit
4 CKP sensor / engine speed (RPM) Crank angle sensor or circuit, ECU
sensor
5 MAP sensor circuit MAP sensor or circuit, mechanical
problem
6 ECT sensor circuit ECT sensor or circuit, automatic
transaxle control unit
7 TPS / Angle Sensor TPS sensor or circuit, automatic
transaxle control unit
8 CKP sensor / engine speed (RPM) Crank angle sensor or circuit, ECU
sensor
9 CMP sensor CMP sensor or circuit
10 IAT sensor IAT sensor or circuit
11 Idle Mixture Adjuster Sensor Idle mixture adjuster sensor or
circuit
12 EGR system fault No EGR action, faulty EGR valve
13 BARO sensor circuit BARO sensor or circuit
14 Idle Air Control valve circuit / ECU Open or shorted out ignition signal
circuit / No signal to ECU
15 Ignition Output signal Open or shorted ignition output
signal circuit
16 Fuel Injector Circuit Open or shorted fuel injector
circuit
17 VSS circuit VSS sensor or circuit
18 Ignition Timing Adjuster Open or shorted signal circuit
19 A/T Lock-up control solenoid Open or shorted signal circuit,
Lock-up control solenoid lock-up solenoid
20 Electrical Load Detector / Sensor Electrical load detector or circuit
Honda/Acura
Fault Code Definitions (21 - 59)
Chapter 3 22
Code Description Possible Cause
21 Spool Solenoid Valve Open or shorted signal circuit,
spool solenoid valve
22 Valve Timing Electronic Oil Open or shorted signal circuit,
pressure switch valve timing oil pressure switch
23 Knock sensor circuit Knock sensor or circuit
30 AT / ECU communication signal A AT control unit, ECU
31 AT / ECU communication signal B AT control unit, ECU
35 Traction control / ECU / signal Traction control module, ECU
36 Traction control / ECU / signal Traction control module, ECU
41 Oxygen sensor heater - left side Oxygen sensor / heater or circuit
42 Oxygen sensor heater - right side Oxygen sensor / heater or circuit
43 Fuel Supply system - left side Oxygen sensor or circuit, fuel
system
44 Fuel Supply system - right side Oxygen sensor or circuit, fuel
system
45 Fuel metering - left side Injector control circuit, incorrect
fuel metering
46 Fuel metering - right side Injector control circuit, incorrect
fuel metering
48 Heated oxygen sensor Oxygen sensor or circuit
53 Right Knock Sensor Right knock sensor or circuit
54 CKP sensor 2 CKP sensor 2 or circuit
59 CMP sensor 2 CMP sensor 2 or circuit

The oxygen sensor is located approximately 10 inches down the exhaust manifold. It looks like a spark plug with wires coming out of it. Most of the time there are two or more depending on which motor you have. Hope this helps!

Fig. Component Location Chart-2000 MPV

1 PCM 2 Mass air flow (MAF)/intake air temperature (IAT) sensor 3 Throttle position (TP) sensor 4 Fuel tank pressure sensor 5 Engine coolant temperature (ECT) sensor 6 Crankshaft position (CKP) sensor 7 Camshaft position (CMP) sensor 8 Knock sensor 9 Heated oxygen sensor (HO2S) (front, LH) 10 Heated oxygen sensor (HO2S) (front, RH) 11 Heated oxygen sensor (HO2S) (rear, LH) 12 Heated oxygen sensor (HO2S) (rear, RH) 13 EGR boost sensor 14 Power steering pressure (PSP) switch 15 Main relay


Fig. Component Location Chart-2001 MPV

1 PCM 2 Mass air flow (MAF)/Intake air temperature (IAT) sensor 3 Throttle position (TP) sensor 4 Engine coolant temperature (ECT) sensor 5 Crankshaft position (CKP) sensor 6 Camshaft position (CMP) sensor 7 Knock sensor 8 Heated oxygen sensor (HO2S) (front, LH) 9 Heated oxygen sensor (HO2S) (front, RH) 10 Heated oxygen sensor (HO2S) (rear, LH)* 11 Heated oxygen sensor (HO2S) (rear, RH)* 12 EGR boost sensor


Fig. Component Location Chart- 2002-06 MPV