Mechanics

ENGINE LIGHT STILL ON - ERROR CODES

1997 Mercury Villager

Computer problem
1997 Mercury Villager 6 cyl Front Wheel Drive Automatic 145000 miles

After initially reading error code P0135, I replaced both Front and Rear Oxygen sensors. Made sense to change both original sensors given their vintage. However, the check engine light continues to stay on.

After driving 250miles checked again for error codes. Now I have these 2 codes to contend with -- P0135 and P0130.

Will greatly appreciate suggestions to fix.

These days I am trying to do self-maintenance to save $$s and will prefer to repair this myself unless impossible to do so at home.
Avatar
Kalyanpur
March 21, 2009.




TESTS W/CODES -1997 Mercury Villager LS

Diagnostic Aids
Perform this test when instructed during QUICK TEST or if directed by other test procedure. This test is intended to diagnose the following: ? HO2S and heater.
? HO2S and sensor connection.
? Vacuum systems.
? Fuel injector and/or fuel injector circuitry.
? Powertrain Control Module (PCM).
? Harness circuits; HO2S, HO2SH, INJ 1-6 and VPWR.

NOTE: HO2S may be displayed on scan tool as 02S.

Circuit Breakout Box Pin No. PCM Pin No. Wire Color HO2S11 26 46 Lt. Green HO2SH11 83 85 Black HO2S12 78 52 White HO2SH12 84 86 Yellow INJ1 69 72 Green/Orange INJ2 74 77 Green INJ3 71 74 Green/Red INJ4 76 79 Yellow/Purple INJ5 79 81 Yellow/Green INJ6 82 84 Green/Blue KAPWR 67 70 Yellow
TEST DIRECTORY
Action Go To Step 1) Go To Step 20) Go To Step 40)
NOTE: DTC P0130 indicates upstream HO2S fault. DTC P0136 indicates downstream HO2S fault.
DTC P0130 & P0136 P0135 & P0141 P0171 & P0172
1) DTC P0130 & P0136: HO2S Circuit Malfunction DTCs P0130 and P0136 indicate an

irrational value in upstream HO2S circuit. Possible causes for fault are as follows: ? Damaged upstream HO2S or circuit.
? Intake air system malfunction.
? Fuel system malfunction.
? Exhaust system leak.
? Ignition system malfunction
Turn ignition off. Connect NGS scan tool to OBD - II DLC. Start engine and run until engine is at normal operating temperature. Access HO2S PIDs. Run engine at different speeds while observing HO2S PID. If HO2S PID is not constantly varying between 0.4-1.0 volt, go to step 11). If HO2S PID is 0.4-1.0 volt and constantly varying, HO2S is okay at this time. Go to CIRCUIT TEST Z or see test procedures in the TESTS W/O CODES article for intermittent diagnostic procedure.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 1) to step 11). No test procedures have been omitted.
11) Check HO2S Output Voltage Warm engine to normal operating temperature. Turn ignition off. Connect NGS scan tool to OBD-II DLC. Access HO2S PIDs. Start engine and run at 2000 RPM while observing HO2S PID. If HO2S reaches 0.6 volt or greater, go to step 14). If HO2S never reaches 0.6 volt, go to next step. 12) Check HO2S Circuit Continuity Turn ignition off. Disconnect suspect HO2S connector. Disconnect PCM connector. Inspect connector for damaged pins and repair if necessary. Install breakout box (leave PCM disconnected). Measure resistance between suspect HO2S harness connector and appropriate breakout box test pin (No. 26 or 78). If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open HO2S circuit. Repeat QUICK TEST.
13) Check HO2S Signal Short To Ground Turn ignition off. Disconnect suspect HO2S sensor. Install breakout box (leave PCM disconnected). Measure resistance between breakout box test pin No. 26 or 78 and ground. If resistance is less than 10,000 ohms repair short to ground in HO2S circuit. Repeat QUICK TEST. If resistance is greater than 10,000 ohms, perform step 40). If all systems are okay in step 40), go to step 15). 14) Check For Short To Power Turn ignition off. Disconnect suspect HO2S sensor. Install breakout box (leave PCM disconnected). Turn ignition on. Measure voltage between breakout box test pin No. 26 or 78 and pin No. 67 (VPWR). If one volt or more is present, repair short to power in HO2S circuit. If less than one volt is present, go to step 40). If all systems are okay in step 40), go to step 15). 15) Erase DTCs Erase DTCs from memory. See CLEARING CODES. Run engine at 1500-2000 RPM for at least 3 minutes. Repeat QUICK TEST. If DTC P0130 or P0136 returns, replace HO2S in question. If DTC P0130 or P0136 does not return, fault is intermittent.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 15) to step 20). No test procedures have been omitted.

NOTE: DTC P0135 indicates upstream HO2S heater circuit fault. DTC P0141 indicates downstream HO2S heater fault.
20) DTC P0135 & P0141: Heater Circuit Malfunction DTC P0135 and P0141 indicate a malfunction in HO2S heater circuit. Possible causes for malfunction are as follows: ? Faulty or damaged HO2S.
? Poor harness connection.
? Open or short in heater circuit.
? Open heater GND circuit.
? Faulty PCM.
Examine HO2S harness connectors for damage or corrosion etc. Repair connectors as necessary. If HO2S harness connectors are okay, go to next step.
21) Check HO2S Heater PID Turn ignition off. Connect NGS scan tool to OBD-II DLC. Access HO2SH PID. Start engine and run at 2000 RPM while observing PID data. If PID indicates ON for approximately 4 minutes after engine is started, go to step 23). If HO2SH PID indicates ON for longer than 4 minutes after engine is started, go to next step. If HO2SH PID does not indicate ON at all, go to step 23). 22) Check HO2SH Circuit For Short To Ground Turn ignition off. Disconnect suspect HO2S sensor. Install breakout box (leave PCM disconnected). Measure resistance between breakout box test pin No. 83 or 84 and ground. If resistance is less than 10,000 ohms, repair short to ground in sensor heater circuit. Repeat QUICK TEST. If resistance is greater than 10,000 ohms, go to next step. 23) Check VPWR Circuit Continuity Turn ignition off. Disconnect suspect HO2S sensor. Turn ignition on. Measure voltage at VPWR terminal at HO2S harness connector (Blue/Yellow wire) and ground. If voltage is greater than 10.5 volts, go to next step. If voltage is less than 10.5 volts, repair open VPWR circuit. Restore all electrical connections and repeat QUICK TEST. 24) Check HO2S Heater Circuit Continuity Turn ignition off. Disconnect suspect HO2S sensor. Install breakout box (PCM disconnected). Measure resistance between HO2SH terminal at harness connector of suspect sensor and appropriate breakout box test pin (No. 83 or 84). If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open HO2SH circuit. Restore electrical connections repeat QUICK TEST. 25) Check HO2S Heater Turn ignition off. Disconnect suspect HO2S. Measure resistance between Blue/Yellow wire and Black wire (component side). If resistance is approximately 6 ohms, replace PCM. Restore electrical connections and repeat QUICK TEST. If resistance is not approximately 6 ohms, replace HO2S. Restore electrical connections and repeat QUICK TEST.
NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 25) to step 40). No test procedures have been omitted.
40) DTC P0171 & P0172: Fuel Trim Malfunction DTC P0171 indicates cylinder bank No. 1 air/fuel ratio too lean or rich. DTC P0172 indicates cylinder bank No. 2 air/fuel ratio too lean or rich. Possible causes for malfunction are as follows: ? Excessive fuel pressure.
? Leaking fuel injector(s).

? Leaking fuel pressure regulator.
? Low fuel pressure.
? Restricted fuel injectors.
? Faulty HO2S or circuit.
? Induction system air leaks.
? Restricted air filter.
? Faulty PCV system.
? Engine mechanical problem.
? Oil level over full.
? Ignition system malfunction.
If any of the above areas are faulty, repair as necessary. If all of the above areas are okay, go to next step.
41) Fuel Pressure Check Connect fuel pressure gauge to fuel rail or fuel filter. Start engine and observe fuel pressure. For fuel pressure specifications, If fuel pressure is as specified, go to next step. If fuel pressure is not
as specified, go to CIRCUIT TEST HC. 42) Check Fuel Pressure Leakdown With fuel pressure gauge installed, turn ignition switch on and off several times. Turn ignition off and observe fuel pressure gauge. If fuel pressure drops less than 5 psi in one minute, go to next step. If fuel pressure drops 5 psi or more in one minute, check for external leaks. If no external leakage is found, check fuel injectors, fuel pressure regulator and fuel pump check valve for internal leakage. 43) Check Injector Circuit Resistance Turn ignition off. Disconnect negative battery cable. Disconnect PCM and inspect connector for corroded or pushed out pins etc, repair as necessary. Install breakout box (leave PCM disconnected). Measure resistance between breakout box test pin No. 67 (KAPWR) and fuel injector test pins. See Fig. 15. If resistance is 10-14 ohms, circuit is okay, go to step 46). If resistance is not 10-14 ohms, go to next step. 44) Check Injector Harness Turn ignition off. Breakout box installed (PCM disconnected). Disconnect injector harness connectors. Measure resistance between breakout box test pin No. 67 (KAPWR) and KAPWR terminal at each injector harness connector. See Fig. 15. If resistance is less than 5 ohms, go to next step. If resistance is greater than 5 ohms, repair open harness circuit as necessary. Restore electrical connections and repeat QUICK TEST. 45) Check Injector Harness For Short Turn ignition off. Breakout box installed (PCM connected). Disconnect suspect injector harness connector. Measure resistance between breakout box test pins No. 67 (KAPWR) and 43 (GND) and 50 (SIG RTN). Measure resistance between injector signal pin and ground. If all resistance measurements are greater than 10,000 ohms, go to next step. If any resistance measurement is less than 10,000 ohms, repair shorted circuit. Restore all electrical connections and repeat QUICK TEST. 46) Check Injector Driver Turn ignition off. Breakout box installed (Connect PCM). Connect a standard non-powered test light between breakout box test pin No. 67 KAPWR and each injector test pin. . Crank engine. If test light dimly glows while cranking, remove breakout box and go to next step. If test light does not glow or glows brightly, replace PCM. Restore electrical connections and repeat QUICK TEST. 47) Check Injector Flow Using Rotunda Fuel Injector Tester Cleaner (164-R3759). Replace any injectors that are not within leakage and flow specification. If all injectors are within leakage and

BMRFIXIT
Mar 23, 2009.


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