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PO122 Diagnostic and Starting Issues on 2001 Oldsmobile Alero with 3.4L V6

Model: 2001 Alero Fault Code: P0122 Posted: 2011-09-27 19:29

I'm working on my 2001 Oldsmobile Alero equipped with a 3.4L V6 engine and automatic transmission. The vehicle will not start fully — it turns over, idles briefly during cranking, then stops. Applying starter fluid allows it to get close to starting but quickly dies afterward. The only fault codes detected are PO122 (Throttle Position Sensor Range/Performance) and PO440 (Evaporative Emission System Malfunction). I know PO44-0 is unrelated to the starting issue. This problem has recurred several months ago; previously, I didn't scan the system but instead disassembled and cleaned the air intake manifold. Recently, I also replaced a clogged catalytic converter. Over the past six months, the vehicle has exhibited poor idle performance. On cold days, it surges; on hot days, it cuts out completely. I've tested the Throttle Position Sensor (TPS) and found consistent readings: 0.55V with ignition on but engine off, rising to approximately 4.0V during cranking with full throttle — both within expected ranges. The reference voltage wire and ground connection are also confirmed as good. Upon inspection, the air intake valve was found to be sticking; I replaced it, but the issue persists. Fuel pump and filter pressure tests show normal readings. My question: Could a faulty Throttle Position Sensor still cause starting problems even if voltage readings appear correct? What other components or systems should I investigate? Thanks, Adam

Related fault codes
P0122
Comments (3)
Anonymous 2011-09-28 05:13

If removing the TPS does not allow the vehicle to start, then it's unlikely that the sensor is the root cause — focus instead on fundamental engine operation requirements like fuel delivery and ignition timing.

Anonymous 2011-09-29 09:50

I checked spark last night and confirmed it’s good. I connected a fuel pressure gauge to the fuel rail and read zero pressure. This suggests a potential failure in the fuel pressure regulator, as I can hear the pump cycling when the ignition is first turned on.

Anonymous 2011-09-29 19:13

Just because the fuel pump is audible doesn’t mean it’s delivering fuel under proper pressure. Most failing fuel pressure regulators don't cause zero readings — instead, they typically bleed off pressure when the key is off and result in a rich idle condition.