Check eng light {follow up}

[samsontdog]

I posted on here that the check eng light was on in my 2003 F250 Ford V10 eng with 105K miles. Took into the local Stealership
and after 3 hrs the Tech said I need a new compter that cost $900

I took it to Auto Zone and 3 error codes came up that stated the
Oxygen Sensor {02 Wiring needs replacing

PO155 02 Heater Circuit Bank # 2 Sensor 1
PO135 02 Heater Circuit Bank # 1 Senser 1
PO141 02 Heater Circuit Bank # 1 Senser 2

Needless to say I will not take it back to AlexXXXXX Ford here
in Yuma

[PaulJ2]

I'm going with wiring harness damage most likely at one of the sensor connections. After all these operate in a very hot environment.

[samsontdog]

carringb wrote:
Three O2 sensor circuit codes is probably NOT the sensors OR the computer. This is either a damaged wiring harness, or simply a loose ground. A loose ground isn't uncommon on RVs because the coach builders often piggy back off the factory grounds instead of installing new ground lugs.

The O2 sensor heater circuit does need both a power and ground wire. It is not grounded through the exhaust. If neither shop tested both the ground and power wires at the sensors, you did not get the diagnosis you paid for. Yes, the PCM does supply and monitor power to the oxygen sensors, but before blaming the PCM, wiring at the sensors has to be checked first. After that is verified, then the power supply can be measured at the PCM to verify a bad board, but the sensor need to be checked first because the only way the board fails is if theres a short somewhere in the oxygen sensor circuit! Failing to fix the root cause, in case of a bad PCM, will only you earn you another new PCM in short order.

Thank You. I will copy this and show to the Tech at Ford Monday when I take P/Up in for modem change

[carringb]

Three O2 sensor circuit codes is probably NOT the sensors OR the computer. This is either a damaged wiring harness, or simply a loose ground. A loose ground isn't uncommon on RVs because the coach builders often piggy back off the factory grounds instead of installing new ground lugs.

The O2 sensor heater circuit does need both a power and ground wire. It is not grounded through the exhaust. If neither shop tested both the ground and power wires at the sensors, you did not get the diagnosis you paid for. Yes, the PCM does supply and monitor power to the oxygen sensors, but before blaming the PCM, wiring at the sensors has to be checked first. After that is verified, then the power supply can be measured at the PCM to verify a bad board, but the sensor need to be checked first because the only way the board fails is if theres a short somewhere in the oxygen sensor circuit! Failing to fix the root cause, in case of a bad PCM, will only you earn you another new PCM in short order.

[Me_Again]

Yak wrote:
You have 3 heater circuit codes, I'll bet there's melted wires somewhere. I'm looking to see what's in common

What is the OP going to think after another 900 or top of 400 if you are correct? Chris

[samsontdog]

After spending $400 + on replacing the sensors,which did not correct the problem other than saying it is the computer. Will be replaced Monday at the Ford Dealership for $900 . I should have got it fixed there in the first place
The $400 repair bill was at Accurate Automotive in the Yuma Foothills. They also wanted $1,350 for rebuilt modem where Ford will install new modem for $900

[Wild_Card]

Most likely computer. Ford techs have computer programs that talk tonthe on board modules. They cm tell what the deal is.

[drsteve]

Ductape wrote:
Wiring shorted on my Jeep and took out a circuit in the computer. So the original advice may not be wrong.

What he said. O2 sensor codes can have several causes, and Ford techs have more training than parts store clerks.

[Trackrig]

path1 wrote:

Trackrig wrote:
As you did, I'd have gotten a second opinion, but you don't know which fix is the correct one yet. Hope it's the Auto Zone one. But considering the price is right, why not go by NAPA also and get them to test it.

Bill

In Yuma there is a NAPA "certified" garage called "310 Auto" and "310 Diesel". Avoid at all costs. Owned by same family, very poor service IMO. Warranty not worth the paper written on.

The actual NAPA part store is other end of town and very helpful, at least to me.

Yes, a NAPA parts store and a shop that uses parts from NAPA are two different things. The shop will most likely to check your codes and the parts place will not.

Bill

[Ductape]

Wiring shorted on my Jeep and took out a circuit in the computer. So the original advice may not be wrong.

There's a company in Miami sells remanufactured computers less costly than most. They're on the web.

allcomputerresources.com

[samsontdog]

Yak wrote:
This unit only has 3 O2 sensors, 2 upstream and 1 downstream. These codes show a issue with the heater circuit of the O2s not the sensor part. They do have one fuse in common. The heater helps the O2 on cold starts

Thank You

[samsontdog]

Yak wrote:
You have 3 heater circuit codes, I'll bet there's melted wires somewhere. I'm looking to see what's in common

Thanks

[samsontdog]

path1 wrote:

Trackrig wrote:
As you did, I'd have gotten a second opinion, but you don't know which fix is the correct one yet. Hope it's the Auto Zone one. But considering the price is right, why not go by NAPA also and get them to test it.

Bill

In Yuma there is a NAPA "certified" garage called "310 Auto" and "310 Diesel". Avoid at all costs. Owned by same family, very poor service IMO. Warranty not worth the paper written on.

The actual NAPA part store is other end of town and very helpful, at least to me.

Thanks for the update

[Yak]

This unit only has 3 O2 sensors, 2 upstream and 1 downstream. These codes show a issue with the heater circuit of the O2s not the sensor part. They do have one fuse in common. The heater helps the O2 on cold starts

[enblethen]

Fuse is I common but should have fourth code as in one of my rigs. All four oxygen sensor off one ten amp fuse.
Intake issue is what I am thing MAF sensor, wet or dirty air cleaner.
Air must go in to come out!