Check Engine Light, Code PO 155
Thread Starter
|
Junior Member
Joined: Mar 2002
Posts: 9
Likes: 0
From: North Carolina
Check Engine Light, Code PO 155
I replaced all of the O2 sensors on this truck (96 with a 302) and I'm still getting a code for a bad O2 sensor.
I had the truck rescanned today at 3 different places. 1st stop Advance, their machine said that all 3 O2 sensors were bad. Next, my local car repair shop, their Snap-On scanner read PO 155. Next stop the Ford dealership. He ran a loooong scan on it and his machine came back that everthing was working properly. He said that if the CEL popped back on that I would have to "bite the bullet" and let a tech go over all of the componets with a fine tooth comb. Well as soon as I fired the truck up, BAM the light was on again. BTW, he ran this test with what looked like a laptop computer but a little bigger. He said that it has pretty much replaced the "break out box"
Suggestions?
I had the truck rescanned today at 3 different places. 1st stop Advance, their machine said that all 3 O2 sensors were bad. Next, my local car repair shop, their Snap-On scanner read PO 155. Next stop the Ford dealership. He ran a loooong scan on it and his machine came back that everthing was working properly. He said that if the CEL popped back on that I would have to "bite the bullet" and let a tech go over all of the componets with a fine tooth comb. Well as soon as I fired the truck up, BAM the light was on again. BTW, he ran this test with what looked like a laptop computer but a little bigger. He said that it has pretty much replaced the "break out box"
Suggestions?
Senior Member
Joined: Oct 2002
Posts: 7,295
Likes: 125
From: St. Louis (Out in the woods)
Actually, you're NOT getting a code that says you have a bad O2 sensor. You're getting a code that says the computer cannot properly test the heater circuit of one of the sensors. There are no codes that specifically say that a part is defective.
Here is the FIRST step of diagnosing a P0155. Notice all the possibilities?
Breakout boxes haven't been used much since before the 96 model year. They're still around, but the computerized scan tools have taken over much of their old jobs.
Steve
Here is the FIRST step of diagnosing a P0155. Notice all the possibilities?
Diagnostic Trouble Codes (DTCs) P0135 P0141, P0155 and P0161 indicate a short to ground, open, or short to VPWR in the HO2S heater circuit.
DTC/HO2S Reference List:
DTC P0135 = HO2S HTR-11
DTC P0141 = HO2S HTR-12
DTC P0155 = HO2S HTR-21
DTC P0161 = HO2S HTR-22
Possible causes:
-- Shorts to VPWR in harness or HO2S.
-- Water in connectors.
-- Cut or pulled wires.
-- Disconnected wiring.
-- Open VPWR circuit.
-- Open GND circuit.
-- Low battery voltage.
-- Corrosion or poor mating terminals.
-- Damaged HO2S heater.
-- Damaged PCM.
l NOTE:
On some applications, a vehicle hoist is required to access the HO2S harness.
Visually inspect the HO2S circuit for exposed wiring, contamination, corrosion and proper assembly.
l Were any concerns found during the visual inspection?
Yes
REPAIR any concerns found in the visual inspection. COMPLETE PCM Reset to clear DTCs. RESTORE vehicle. RERUN «Quick Test».
No
GO to «H31».
DTC/HO2S Reference List:
DTC P0135 = HO2S HTR-11
DTC P0141 = HO2S HTR-12
DTC P0155 = HO2S HTR-21
DTC P0161 = HO2S HTR-22
Possible causes:
-- Shorts to VPWR in harness or HO2S.
-- Water in connectors.
-- Cut or pulled wires.
-- Disconnected wiring.
-- Open VPWR circuit.
-- Open GND circuit.
-- Low battery voltage.
-- Corrosion or poor mating terminals.
-- Damaged HO2S heater.
-- Damaged PCM.
l NOTE:
On some applications, a vehicle hoist is required to access the HO2S harness.
Visually inspect the HO2S circuit for exposed wiring, contamination, corrosion and proper assembly.
l Were any concerns found during the visual inspection?
Yes
REPAIR any concerns found in the visual inspection. COMPLETE PCM Reset to clear DTCs. RESTORE vehicle. RERUN «Quick Test».
No
GO to «H31».
Steve