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PO221 and P2135 Codes in Jeep Patriot: Throttle Position Sensor Issue and PCM Diagnosis

Model: Jeep Patriot Fault Code: P0221 Posted: 2021-10-16 04:29

The vehicle is displaying both PO221 and P2135 diagnostic trouble codes, with the MIL (Malfunction Indicator Lamp) activated. This issue has been recurring across multiple repair shops. The throttle body was recently replaced, yet the problem persists. During scanning, I've observed intermittent drops in voltage on Accelerator Pedal Position (APP) Circuit 2 — the signal randomly falls to zero, and this behavior is not reproducible by manually manipulating wiring harnesses. Given that the pedal has been replaced multiple times and the throttle body has also been serviced, I suspect a deeper issue. The symptoms point toward a potential failure in APP Circuit 2, possibly originating at the PCM or within the sensor assembly itself. I am currently considering replacing the accelerator pedal with a known-good unit to isolate the fault. However, I would like input from others who have encountered this specific combination of codes on Jeep Patriots — especially those with 2.4L VVT engines. My goal is to stop relying on guesswork and confirm whether this is a wiring issue, sensor failure, or a PCM-related problem.

Related fault codes
P0221P2135
Comments (11)
Anonymous 2021-10-16 06:18

Jeep Patriot — please specify the model year and engine size for more accurate troubleshooting guidance.

Anonymous 2021-10-16 06:28

Have you performed a voltage or signal scope test on APP Sensor 1 and APP Sensor 2? The scan tool shows APP Circuit 2 dropping to zero. Why was the throttle body replaced, especially if the issue is in the pedal position circuit?

Anonymous 2021-10-16 13:14

This is a 2015 Jeep Patriot with a 2.4L VVT engine. The throttle body was previously replaced due to these exact codes. I haven't done any signal scoping because I can directly observe the voltage dropping to zero on the scan tool. It appears that APP Circuit 2 is faulty — likely not the pedal itself, but possibly a PCM issue. I plan to test with a known-good accelerator pedal next week.

Anonymous 2021-10-17 01:18

If you back-probe the APP Sensor 2 signal at the PCM and observe a drop in voltage, it may indicate a bad wire or faulty sensor assembly. If the signal drops at both the sensor and the PCM, then the issue is likely within the wiring harness or the sensor circuit. Always verify power and ground connections before replacing components. Ensure that each APP sensor has its own dedicated 5V reference and ground circuits — these are typically separate to maintain signal integrity.

Anonymous 2021-10-17 06:08

I'll check whether there are separate 5-volt references and grounds for each APP sensor. It seems likely that such a design exists. I may end up doing what you suggested — testing the signal at both the sensor and PCM. I hate disassembling the PCM connector, but it's accessible. Maybe I’ll use a piercing probe to temporarily fix a bad wire and seal it with silicone later. Honestly, I just don’t want to keep guessing.

Anonymous 2021-10-18 02:39

I understand — I’ve used piercing probes myself. My favorite is Phil’s 11-inch model with multiple fine needles for penetrating insulation. Others use a single hole and seal it with liquid electrical tape, which I've also tried at Walmart.

Anonymous 2021-10-18 09:31

Confirmed: separate 5V reference voltage and ground circuits exist for each APP sensor. This design helps prevent signal interference. Best of luck with your diagnosis!

Anonymous 2023-01-17 00:24

Did you resolve this issue? I'm experiencing the same PO221 and P2135 codes on my Jeep Patriot — it seems to be a common problem, but no one has found a reliable fix yet.

Anonymous 2023-01-22 07:05

Mindriot wrote: Tue Jan 17, 2023 12:24 am Did you resolve this issue? I am getting the same codes. It seems to be pretty common with Jeep Patriots and no one can seem to find a solution. My case was resolved by replacing the PCM — which isn’t surprising given the persistent symptoms.

Anonymous 2023-05-25 01:44

Elijah86 wrote: Thu May 25, 2023 1:22 am PO221 and P2135 codes in a Jeep Patriot indicate issues with the throttle position sensor or accelerator pedal position sensor. These faults can lead to poor engine performance or stalling. Accelerator pedal has been replaced three times, throttle body six times, PCM once — yet the codes persist. The vehicle runs fine under normal conditions. This suggests the issue may be intermittent or related to signal noise rather than a critical failure.

Anonymous 2023-10-14 11:13

RandomGuessing wrote: Sun Jan 22, 2023 7:05 am My situation ended up being the PCM — which isn’t really surprising. This supports the idea that a faulty PCM may be causing intermittent APP signal drops.