HEGO, VMV, CMS, PTEC - 1997 Mercury Mountaineer

dead short after the fuse
isolate each item that the fuse runs until you find the faulty unit

171 is a HEGO sensor unable to switch/ 174 is for HEGO sensor also.. 401 is insufficient EGR flow!! egr valve may be clogged or need replaced!!

fusee blow because of excess current caused by a short either in the wires after the fuse or in the equipment that the fuses controls.

In the power distribution box in the engine compartment : fuse # 41 is a 15 amp fuse for HEGO ( Heated Exhaust Gas Oxygen - sensors ) , VMV ( Vapor Management Valve ) , CMS ? and PTEC ( which I believe stands for Powertrain Electronic Controller )

Hi Vanessa,

Diagnostic Test Code (DTC) P1443 has a "generic" description of "Very Small Or No Purge Flow Condition"
To put it very simply, the Powertrain Control Mdule (PCM) is commanding the Canister Purge (CANP) solenoid to open and purge the fuel vapors from your charcoal canister and fuel tank. Then it "looks" at data from the Purge Flow (PF) sensor to see if if the CANP solenoid complied with its command. This is not occuring as it should. (see the picture below to see how all these parts work together)

Here is a list of the possible causes of this code:
> Leaks in fuel tank, filler cap or vapor hoses
> Wiring harness circuits (CANP SIG, PF, PWR GND, VMV and VPWR)
> Faulty Canister Purge (CANP) solenoid
> Faulty Purge Flow (PF) sensor
> Faulty Vapor Management Valve (VMV)
> Faulty carbon canister
> Faulty PCM
The system must be diagnosed to find out which parts of the system are functioning correctly and which are not, so the fault can be found. The computer only knows that the data from the PF sensor is not what it should be - it does not know WHY.

it has to do with a short in the wiring so you can use a multimeter to see where the short is at. make sure you use the multimeter properly so you do not blow the multimeter. you can buy one at wal mart around 20 dollars or so.

check the HEGO sensor (upstream) first. Check for a broken wire in the harness to the sensor. Good luck. The HEGO sensor in in the exhasut system just past the exhaust manifold.
The downstream sensor is not so important.



P1151 - Lack of HO2S-21 Switch, Sensor Indicates Lean A HEGO sensor indicating lean at the end of a test is trying to correct for an over-rich condition. The test fails when fuel control system no longer detects switching for a calibrated amount of time. See Possible Causes for DTC P1130

P1130 - Lack of HO2S-11 Switch, Fuel Trim at Limit The HEGO Sensor is monitored for switching. The test fails when the HO2S fails to switch due to circuit or fuel at or exceeding a calibrated limit.

• Electrical:
  • Short to VPWR in harness or HO2S
  • Water in harness connector
  • Open/Shorted HO2S circuit
  • Corrosion or poor mating terminals and wiring
  • Damaged HO2S
  • Damaged PCM
• Fuel System:
  • Excessive fuel pressure
  • Leaking/contaminated fuel injectors
  • Leaking fuel pressure regulator
  • Low fuel pressure or running out of fuel
  • Vapor recovery system
• Induction System:
  • Air leaks after the MAF
  • Vacuum Leaks
  • PCV system
  • Improperly seated engine oil dipstick
• EGR System:
  • Leaking gasket
  • Stuck EGR valve
  • Leaking diaphragm or EVR
• Base Engine:
  • Oil overfill
  • Cam timing
  • Cylinder compression
  • Exhaust leaks before or near the HO2S(s)

A fuel control HO2S PID switching across 0.45 volt from 0.2 to 0.9 volt indicates a normal switching HO2S.

switch, we run off snitches. 171 174 banks 1 & 2 Lean. Most likely cause are Upper Intake Manifold Gaskets, failed seals. It's not 1990 on. It's 1996 and on OBD2.

Without more information or testing its impossible to help diagnose this problem. However, when is the last time the oxygen sensor been replaced. My best guess in this situation and remember that this is not a easy item to replace as it is located within the exhaust system and is usually corroded.

Here is the first half of the codes look till you find the one you have
111 System PASS.
112 ACT sensor circuit grounded.
113 ACT sensor circuit open.
114 ACT sensor is out of Self-Test.
116 ECT sensor is out of Self-Test.
117 ECT sensor circuit grounded.
118 ECT sensor circuit open.
121 TP sensor is out of Self-Test.
122 TP sensor input is less than Self-Test minimum.
123 TP sensor input is greater than Self-Test maximum.
124 TP sensor input voltage is greater than expected.
125 TP sensor input voltage is less than expected.
128 MAP vacuum hose damaged or disconnected.
129 Insufficient MAF input.
136 HEGO sensor circuit indicates system lean (Right HEGO).
137 HEGO sensor circuit indicates system rich (Right HEGO).
139 No HEGO switching (Front Side).
141 Fuel system indicates lean.
144 No HEGO switching (Left Side).
157 MAF sensor circuit open.
158 MAF sensor shorted to power.
159 MAF sensor is out of Self-Test.
167 Insufficient TP input change.
171 Lack of HEGO switching (Rear Side).
172 HEGO sensor circuit indicates lean. (Rear Side).
173 HEGO sensor circuit indicates rich. (Rear Side).
174 Check for diluted engine oil.
175 Lack of HEGO switching (Front Side).
176 HEGO sensor circuit indicates lean. (Front Side).
177 HEGO sensor circuit indicates rich. (Front Side).
178 Check for diluted engine oil.
179 Fuel system at part throttle lean adaptive limit, system rich (Rear Side).
181 Fuel system at part throttle rich adaptive limit, system lean (Rear Side).
182 Fuel system at idle lean adaptive limit, system rich (Rear Side).
183 Fuel system at idle rich adaptive limit, system lean (Rear Side).
184 MAF sensor input voltage is greater than expected, in range.
185 MAF sensor input voltage is less than expected, in range.
186 Closed loop injector pulse width longer than expected.
187 Closed loop injector pulse width shorter than expected.
188 Fuel system at part throttle lean adaptive limit, system rich (Front Side).
189 Fuel system at part throttle rich adaptive limit, system lean (Front Side).
193 Flexible Fuel sensor circuit failure.
211 PIP circuit failure.
212 Loss of tachometer/IDM input.
213 EEC SPOUT circuit open.
214 CID circuit failure.
215 PCM detected coil 1 primary circuit failure.
216 PCM detected coil 2 primary circuit failure.
217 PCM detected coil 3 primary circuit failure.
218 Loss of ignition diagnostic monitor signal-left side.
219 Spark timing defaulted to 10 degrees, spark output circuit open.
221 Spark timing error.
222 Loss of ignition diagnostic monitor signal-right side.
223 Loss of dual plug inhibit control.
224 PCM detected coil 1, 2, 3 or 4 primary circuit failure.
225 Knock not sensed during dynamic response test KOER.
226 Ignition diagnostic monitor signal not received.
232 PCM detected coil 1, 2, 3 or 4 primary circuit failure.
238 PCM detected coil 4 primary circuit failure.
241 Ignition control module to PCM ignition diagnostic monitor pulse width transmission error.
244 Cylinder Identification circuit fault present when cylinder balance test requested.
311 Secondary air injection system inoperative during KOER self-test (bank #1).
312 Secondary air injection system misdirected during KOER self-test.
313 Secondary air injection system not bypassed during KOER self-test.
314 Secondary air injection system inoperative during KOER self-test (bank #2)
326 PFE sensor circuit voltage lower than expected.
327 PFE sensor circuit voltage below Self-Test minimum.
328 Exhaust gas recirculation valve position sensor closed voltage lower than expected.
332 Insufficient EGR flow.
334 Exhaust gas recirculation valve position sensor closed voltage higher than expected.
335 PFE sensor circuit voltage out of Self-Test range.
336 PFE sensor circuit voltage higher than expected.
337 PFE sensor circuit voltage above Self-Test maximum.
338 Engine coolant temperature lower than expected (thermostat test).
339 Engine coolant temperature higher than expected (thermostat test).
341 Octane adjust service pin open.
381 Frequent A/C clutch cycling.
411 Cannot control RPM during KOER low RPM check.
412 Cannot control RPM during KOER high RPM check.
415 Idle Air Control system at maximum adaptive lower limit.
416 Idle Air Control system at upper adaptive learning limit.
452 Insufficient input from VSS.
453 Servo leaking down.
454 Servo leaking.
455 Insufficient RPM increase.
456 Insufficient RPM decrease.
457 Speed control command switch(s) circuit not functioning.
458 Speed control command switch(s) stuck/circuit grounded.
459 Speed control ground circuit open.