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check engine light code p0156

2K views 5 replies 3 participants last post by  smokymance 
#1 ·
well its been going on and off and i searched and could not find anything. i know it has to do with the o2 sensors but not exactly what....the car has been running bad too and im thinking its this. (the car is catless too and has MIL eliminators)
 
#2 ·
DTC P0136 and P0156 indicate the output voltage of the downstream HO2S is less than some calibratable functional window. KOER DTCs P1137, P1138, P1157 and P1158 can only be retrieved during KOER Self-Test when the fuel control is ramped rich and lean and monitored for a voltage change on the downstream HO2S.

-- DTC P0136, P1137 and P1138=HO2S-12

-- DTC P0156, P1157 and P1158=HO2S-22

Possible causes:

l Wiring Concerns:

-- Pinched, shorted, and corroded wiring and pins

-- Crossed sensor wires

l Other Concerns:

-- Exhaust leaks

-- Contaminated or damaged sensor

l Are any of the above concerns present?

Yes
SERVICE as necessary. COMPLETE PCM Reset to clear DTCs. RERUN «Quick Test».

No
Continuous Memory DTCs P0136 and P0156:

GO to «H81».

All others:

GO to «H82».

H81 CHECK FOR KOER DTCS P1137, P1138, P1157 AND P1158
l Key off.
l Scan Tool connected.
l Key on.
l Engine at 2000 rpm for 3 minutes.
l Activate KOER Self-Test.
l Check for DTCs.
l Are DTCs P1137, P1138, P1157 or P1158 present?
Yes
GO to «H82».
No
For DTCs P0136 and P0156:
The fault that produced the DTC is intermittent. GO to Pinpoint Test Step «Z1» with the following data: HO2S-12,22 PIDs and list of Possible causes.

H82 CHECK EXHAUST SYSTEM FOR LEAKS

NOTE:
Any exhaust leaks between the engine and the end of the catalyst can cause DTCs P0136 and P0156.
l Key off.
l Place vehicle on a hoist, transmission in PARK, emergency brake applied, raise vehicle.
l Inspect the following:
-- Exhaust flanges for leaks.
-- HO2S torque.
-- Check for punctures and cracks in catalyst and pipes leading to them.
l Are there any exhaust leaks?
Yes
REPLACE or SERVICE as required. COMPLETE PCM Reset to clear DTCs. RERUN «Quick Test».
No
GO to «H83».

H83 CHECK HO2S HARNESS CIRCUIT FOR SHORT TO VPWR AND GROUND
l Key off.
l Disconnect Scan Tool from DLC.
l Disconnect PCM. Inspect both ends of connector for damaged or pushed out pins, moisture, corrosion and loose pins. Service as necessary.
l Install breakout box. Leave PCM disconnected.
l Suspect HO2S disconnected.
l Measure the resistance between HO2S Signal Test Pin and SIG RTN Test Pin at the breakout box.
l Measure the resistance between HO2S Signal Test Pin and VPWR and VREF Test Pin at the breakout box.
l Measure the resistance between HO2S Signal Test Pin and PWR GND Test Pin at the breakout box.
-- HO2S-12 SIG = Test Pin 35
-- HO2S-22 SIG = Test Pin 61
-- HO2S SIG RTN = Test Pin 91
-- PWR GND = Test Pins 24 and 103
-- VPWR = Test Pins 71 and 97
-- VREF = Test Pin 90
l Is resistance greater than 10,000 ohms?
Yes
GO to «H84».
No
SERVICE short in harness. REMOVE breakout box. RECONNECT PCM. RERUN «Quick Test».

H84 CHECK RESISTANCE OF HO2S AND HO2S GROUND CIRCUITS
l Key off.
l Breakout box installed, PCM disconnected.
l Suspect HO2S disconnect from harness.
l Measure the resistance between HO2S Signal Test Pin at the breakout box and the HO2S vehicle harness connector. Record readings.
l Measure resistance between SIG RTN Test Pin at the breakout box and HO2S SIG RTN vehicle harness connector. Record readings.
-- HO2S-12 SIG = Test Pin 35
-- HO2S-22 SIG = Test Pin 61
-- HO2S SIG RTN = Test Pin 91
l Is the resistance reading less than 5.0 ohms?
Yes
GO to «H85».
No
SERVICE open circuit in harness. REMOVE breakout box. RECONNECT all components. RERUN «Quick Test».

get the idea??? if that dont work.. let me know.. i'll post the REST of the 97 service cd instructions..
 
#4 ·
downstream.. says it on the .. uhh.. :D 1st line? downstream is AFTER the cats

for reference, P136 was bank 1 sensor 2, which i keep hearing is passenger side, post cat
 
#5 ·
Just one question.. why did you put MIL elimintators on anyway?? My cougar has straight pipe manifold back customized exhaust and I don't get an MIL (check engine). The only time i get an MIL is when I swapped the 19# inj. for the 24# and I was still running 45psi on idle, now running 30psi w/ 24's.

Clay
 
#6 · (Edited)
i dont know...u need the MIL eliminators without catalytic converters...do u have a chip for it?....i know my car right now is missing hardcore and i just got new wires and plugs...and its still missing...and i hope this is the problem...would it cause it to miss?
 
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