I ran across this error code on a Hyster with a GM V6 4.3L and the unit would run good for a few minutes, start to stumble and then stall.
When restarted, it would smell like sulfur and it would barely run.
Reference: Bank 1 is on the right side of the truck and Bank 2 is on the left.
Error Codes Definition
522655-0 – Short Term Closed Loop Correction Bank 1 Less Than normal-40% (Rich Engine Operation)
522655-1 – Short Term Closed Loop Correction Bank 1 Greater Than normal 40% (Lean Engine Operation)
522655-0 Short Term Closed Loop Correction Bank 1 Rich Condition
Causes of a rich condition
Fuel regulator malfunction
I have seen this as the most common cause. The LPG regulator gets full of a byproduct of LP polypropylene and causes the diaphragm to stick and either causes an increase in pressure or a decrease.
Engine running cool
If the engine is not reaching operating temperature or the engine coolant temperature sensor is telling the ECM it is still cold, the ECM will command more fuel and cause a rick condition.
Fuel injector(s) sticking open
Carbon buildup in the combustion chamber will cause the injectors to become sticky and they will not seat when they close, causing fuel leaks in the combustion chamber.
A clogged or dirty air filter
When the air filter gets clogged and causes a significant air flow restriction, this will case a rich condition.
Bad ignition coil, spark plugs or ignition cables
If the tune-up is bad, there may or may not be other symptoms associated with these code, such as misfiring or stumbling during travel.
There are other uncommon causes for these code as well.
ECM injector drivers or bad ECM grounds. Operating at high altitudes. A faulty LPG carburetor. A faulty Oxygen Sensor.
522655-1 Short Term Closed Loop Correction Bank 1 Lean Condition
Causes of a lean condition
Clogged or contaminated fuel injectors
Clogged injectors will restrict the fuel flow cause the engine to get less fuel than necessary to run properly and maintain the proper fuel mixture.
Fuel regulator malfunction
The regulator’s diaphragm may get worn out and become torn, causing it to fail. This is a common issue with LPG fuel systems and usually causes a no start condition, but it is very possible at the initial stages of wear for the unit to start losing fuel pressure causing a lean condition.
Clogged fuel filter
Seems obvious enough, but yo will be surprised how many technicians miss this step. Especially on the LPG systems where the fuel quality is low.
Engine vacuum leaks
Intake or vacuum hose leaks are common and when this happens, the engine is starving for fuel causing a lean condition.
Clogged fuel Hoses
Over time the LPG hoses can become clogged with the polypropylene.
Malfunctioning fuel lock off
This is more common for a no start condition, however, it is possible for them to get clogged and cause a lean condition as well.
Engine overheating or a faulty coolant temperature sensor
Not one looked at too often, but if the engine is overheating or the ECM thinks that the engine is already at operating temperature, it will reduce the fuel allowed to be injected.
There are other uncommon causes for these code as well.
ECM injector drivers or bad ECM grounds. A faulty LPG carburetor. A faulty Oxygen Sensor.
Oxygen Sensor Testing
The easiest way to test the O2 sensor is to create either a rich or lean condition.
To create a lean condition, simply remove a vacuum hose from the intake and watch the oxygen sensor voltage. (It should drop below .5V)
To create a rich condition, get a propane torch and open the valve. Put the valve into the air cleaner housing allowing the engine to suck in the fuel and this will cause a rich condition. The oxygen sensor voltage should rise above .5V.
Known Causes
These are conditions that have actually caused these codes.
- Bad spark plugs
- Bad ignition coil
- Torn diaphragm in the mixer
- Bad oxygen sensor