enigine code p0122

im getting this code rite after i replaced my TPS today and the car is still bogging down, the code reader says "throttle posotion censor A voltage to low" any idea how i can repair this???

1. Year/engine/trans?

2. What is the TPS reference voltage?

3. What is the TPS output voltage?

its a 97, 4.0, 2wd transmission,

input voltage- 5.0
output voltage- 4.2

ok so the truck is running, idoling and shifting fine now but the check enging light is still on, this time i cylced the key a couple times and the code, 12-55 came up, i know 12 means the battery has been disconected and 55 means end of code, what could this mean....?

12-55 mean nothing. They are the common codes if you do the key click. Get a real scanner, read any codes and reset the MIL. You may also need to reset the ECU to read the new TPS values but it sounds like it's running OK now.

do i need the scanner to reset the ECU? or can it be done manualy? does disconnecting the battery reset it? when it comes to electrial stuff its way over my head.....

Ok, sometime in 97 reading codes with the key was eliminated.

your reference and output voltage at the TPS are good.

You can reset codes by pulling BOTH battery cables off the battery and holding them together for 30 seconds or so.

This very simple procedure will Erase the “Adaptive Memory” stored inside the PCM and allow a new “Adaptive Memory” to be developed.

After performing this procedure the PCM will re-learn and store into Adaptive Memory your engines performance characteristics.

Please perform these steps exactly as they are written, in the order they are written. This will cause the adaptive memory in the PCM to be erased and cause the PCM to go into Fast Learn Mode adaptive mode.

Disconnect the POSITIVE battery Terminal and touch it to ground ( not the battery negative terminal ) for 30 seconds. The engine block or the A/C compressor pump will work as a ground. (This is to discharge the PCM capacitors, which maintain the Adaptive Memory.

Reconnect the Battery Cable
Turn Ignition Switch to the “On” position but DO NOT start the engine
Turn Headlight “On”
Turn Headlights “Off”
Turn Ignition Key “Off”


The PCM Adaptive memory has now been flashed, or erased from the PCM.

When you start the engine it will be running off a set of pre-programmed tables that come with the PCM from the factory.

When you get the engine up to operating temperature the PCM will start to collect data for the “Adaptive Memory”.

The PCM will collect data for Adaptive Memory for the first 50 Warm-up Cycles.

Yeah, what they said.

However <soapbox mode on>, if you have an OBDII vehicle and want to DIY, you should have a code scanner. Cheap ones are under $40. They work on your XJ and *almost* any other 96+ vehicle. I got one from Harbor Freight that reads the CAN protocol as well. <soapbox mode/off>

will that PCM procedure work on a 1996 xj also?

xjhazy21 said:

will that PCM procedure work on a 1996 xj also?

Click to expand...

You mean clearing codes by discharging the PCMs memory by removing both cables from the battery and holding them together? Yes, 91+ XJs can have the PCM memory cleared in this fashion.

ok thanks