VT 5.0 Engine 'trouble'

[Copafield]

Have had the engine light start to come on but it's not every single trip. Have only had about 6 trips so i'm not yet to notice a pattern. DTC codes are 13 (RH Oxygen Sensor - no signal), 35 (Idle speed error (IAC valve unable to control idle speed) and 63 (LH Oxygen sensor - no signal).

Just wondering if anybody has had any experience with these codes. For 13 and 63 i'm going to physically have a look in the morning at the O2 sensors but the IAC has me a little stumped (even with looking at the workshop manual). The engine doesn't appear to be behaving badly nor idling badly or unevenly - the only reason i'm concerned is because of the light. Opinions on whether this is something that can be ignored if not readily solved are also welcomed

[Cheap6]

If you are getting the CEL it's a current fault and should be rectified.

The IAC motor code is probably not a problem - likely caused by a driver induced stall in a manual trans. car.

Having done the code check, clear the PCM memory by disconnecting the "FS Main" fusible link, check the codes to ensure they are cleared and wait for the codes to reoccur. The O2 sensor codes require the engine to be warm, running for a couple of minutes and the fault - O2 sensor voltage staying around 450mV - to be present for 20 seconds.

The only things that both O2 sensors share is the heater circuits - earth and power. The fuse for the power is shared with the MAF sensor, A/C relay and canister purge solenoid so in the absence of faults with them it's probably not that but it's easy to check. The earth is also shared with at least the MAF.

It is possible that both O2 sensors have failed as they will both be of similar age but I think unlikely. You might look for a terminal connector block that they share with loose or dirty connection.

If you have a DMM - they are cheap enough @ ~$20 - you might check the O2 sensor voltages. D13 @ PCM is RH sensor hi, D14 is RH low. D15 LH hi, D16 LH low. You should see ~450mV across each of the hi-low pairs with the sensors cold then a signal varying between 200mV and 800mV with the sensors warm.

[Copafield]

Now this is what i'm talking about Just getting ready for work and will be leaving soon and will check under the car at work ... one other thing worth mentioning though is the air con doesn't appear to work - and seeing as how you mentioned aircon maybe it's the same cause? Thanks for all your help! I do have a DMM somewhere, probably at the shop. Will keep you posted as to what i find - should be by about lunch

[Copafield]

OK, drove to work this morning (35 klm HWY trip + 5 mins of local streets) and the light didn't come on. Got to work, cleared the codes, then went for a more spirited drive and the light came on. Only 1 code this time which is DTC 13 which might simply mean I've got a bad O2 sensor, will have to get it off the ground and have a check. Otherwise everything else appears fine. Will comment again once I take it for a few more drives and/or I get to the O2 sensor.

[Copafield]

Few more drives, haven't even had the light come on. Buggered if I know - unless something happens prior i'll have a check of the sensor when i get the car off the ground to do the rotors.