I have a 1999 Honda Accord LX - Auto transmission and it was running fine a week back till I got CEL with P0113,P0118 and P0123 codes all at the same time. The car stutters during starting, idles well but I have to gas the pedal and rpm raises a lot before it shifts to higher gears - which eventually it does with jerks when it shifts to higher gears suddenly.

I have shown it to 4 shops - 2 of them couldnt figure out what was happening, another 1 said it was a transmission problem and the last one negated that possibility. Frustrated and after searching the web it looks like it might be a case of loose wiring or short circuit but since I am not hands-on, I dont know where to start from to check.

Any help would be deeply appreciated. Thanks in advance.

 

To have the Intake air temperature (IAT) P0113, Engine coolant temperature (ECT) P0118 & Throttle position sensors (TPS) P0123 all go at once it rather odd. Worst case would be that it might be something wrong with the Engine Control Unit/Module (ECU/ECM). However I would start with testing the three sensors and there wiring. The three sensors can easily be checked with a multimeter.

You say you are not hands on, do you own or have access to a multimeter to test the sensors and check the wiring?

Have you done any recent repairs or added any electrical components?

 

Thanks Ghost for your quick response.
I havent done any repairs on the car for more than a year and nothing on the electrical wiring since I bought it 4 years back. 1 odd thing also occured and I dont know whether this has any relevance but 1 day prior to these codes popping up when I was driving the car I switched on the AC and it wouldnt pass any cool air though the fan was ON. Not sure whether it has any bearing but wanted to mention it.

I dont have a multimeter but I know a mechanic who might be able to help me out. What if the multi meter readings come up fine? Is there any plan B?

 

If the readings for the sensors and there wires come up OK. I would look at testing the ECU.

The High input error codes that you are getting indicate an open in the circuit. Check the grounds! IIRC These sensors all have a common ground location.

 

Thanks Ghost. I will try that and let you know what I find out.

 

@GhostAccord is correct. These three components share a common ground at the PCM along with the EGR valve, O2S1, O2S2, and the Fuel tank pressure sensor. Do you have any other DTC's? It would be weird to have a ground issue at the PCM and not have any of these other components cause an issue. With the ignition switch in the on position, back probe the IAT (intake air temperature) sensor on the Green wire with a black stripe (green/black). Back probe with the positive lead and put the negative lead to ground (body ground, battery ground ect..). What kind of voltage do you read? If you get a higher than normal (0.150v) voltage reading, check the ECT and TPS ground wire (same color ground wire as the IAT). That's going to be the easiest location to check before going downstream to the PCM. The IAT is locted on the right side of the intake if you're at the front of the car facing the engine. The only other commonality I see for just those three sensors is junction connector 103 which voltage goes through before reaching the PCM.

 

Hi Ghost, Justin,
I am really grateful to you folks for the suggestions. I asked an auto mechanic to check the things that you mentioned and as you mentioned he found a loose wire. They fixed it and the car seems to be working fine. The car mechanic was reluctant to do it in the first place and was confident that it was a transmission problem but somehow I managed to convince him to do the steps you had given and it worked. Thanks a ton again for your help. Cheers !!!

 

Glad you got it sorted out!

 

Glad everything is ok with your ride.